Valuing a collection and tracking it are two different jobs. A valuation answers what the cards are worth today and is finished the moment you write the number down. Tracking is the ongoing version: keeping a record accurate enough that next month's number can be compared to this month's and the difference means something.
Almost everything that makes tracking useful or useless is decided by how the record is shaped, not by which price source you use. A collection stored as card names produces a total that drifts for reasons you cannot explain. A collection stored as printings — this set, this collector number, this finish, this condition, this many — produces a total you can take apart and account for. That distinction is the whole guide.
Track the printing, not the card name
A price belongs to a specific physical object, and a card name is not one. A widely reprinted card exists in a dozen printings at wildly different prices, so a tracker that holds "4 × Lightning Bolt" has to pick a price, and whichever it picks is wrong for most people who own four.
Five fields turn a name into an object:
- Printing, meaning the set code and collector number together. This is the field that decides which market the copy trades in at all.
- Finish — non-foil, foil or etched. These are priced separately and can differ by an order of magnitude on the same printing.
- Condition, the grade you assigned to the copy in your hand.
- Language, which affects both identification and price.
- Quantity of that exact combination.
Get those right once and every number after them is derived rather than guessed. Get them wrong and no amount of price-feed quality rescues the total. If the collection came in from a file, importing a ManaBox export covers which columns carry these fields and which of them quietly default to something else. If it came in by hand, the card catalog lists a card's printings side by side so you can pick the one you are holding.
Keep a series, not a number
A tracker that stores one current price and overwrites it every night can tell you what your collection is worth. It cannot tell you anything about how it got there, which is the question tracking exists to answer.
What you want is a series: a price with a date attached, kept as history. It does not need a reading every day. Most cards do not move most days, so a record that captures a price when it changes and leaves it alone otherwise carries exactly the same information as a daily reading, at a fraction of the size. A flat stretch in a chart and a gap in the underlying data are the same fact.
Two things follow from that, and both are easy to get wrong when reading a chart:
- A line that does not move is data, not a missing reading. Cards that hold their price for months are the normal case, not a broken feed.
- History has a horizon. Any tracker keeps a finite window — a rolling few months is typical — so the comparison you want to make in a year has to be made from records you started keeping today. There is no way to backfill a price series you were not collecting.
That last point is the argument for setting tracking up before you need it. The cost of starting is one import; the cost of not having started is that your first useful comparison is a quarter away.
Know what your price is actually measuring
Every public Magic price feed quotes one figure per printing and finish, and that figure describes a clean copy. Condition is not in the feed, because no public source publishes a per-condition price for every card.
This matters more than it sounds. A shelf of heavily played commons priced against near-mint figures values exactly the same as a pristine copy of each, which overstates what the collection could actually fetch — sometimes badly, on an old and well-loved collection. The fix is not to distrust the feed but to apply the discount on top of it, as an explicitly labelled estimate: roughly 85% of the clean price for a lightly played copy, 70% for moderately played, 50% for heavily played, and less again for damaged. Those are the rule-of-thumb ratios storefronts price around, not a quote from any one of them, and real spreads vary by card. Grading a card covers assigning the grade the discount applies to.
Keep the two numbers separate rather than baking the discount into what you store. The clean market figure is what price history and any marketplace pricing depend on; the adjusted figure is what you want when you are asking what the collection would realistically fetch. How much is my collection worth covers the wider version of that question, including buylist and after-fee figures.
Watch the top of the collection, not all of it
In almost any collection a small number of cards carry most of the value, and those same cards carry most of the movement in absolute terms. A 20% swing on a bulk rare is noise; the same swing on your most expensive card is the only line in the total that changed.
So set the rhythm by value rather than by count. Re-check the top of the collection regularly and leave the tail alone until something gives you a reason to look at it. The things that give you a reason are worth learning as a short list, because each of them moves prices sharply and none of them are visible in a total you calculated last month:
- Reprints, which increase supply and usually move a price down hard.
- Format legality changes, which move demand in either direction overnight.
- A shift in what people are building, which is slower but compounds.
A tracker helps here mostly by being a movers list rather than a total: the useful daily question is not "what is my collection worth" but "which of my cards changed, and by how much".
Write down what a change means before you see one
The failure mode of good price tracking is reacting to it. A number that updates every day invites a decision every day, and most days there is no decision to make.
Decide your rules in advance, in writing. A reasonable set: only look at movers above a value threshold, only act on a move that persists for more than a few days, and always cross-check against the venue you would actually sell on before doing anything — every source lags the market, and after a sharp move that lag is the entire difference between two figures.
Then connect the tracking to something you would actually do. For most collectors that is trading rather than selling, which makes the useful pairing "cards that moved" against "cards I would part with" — see building a trade binder for keeping that second list honest.
Doing this in ManaArchive
ManaArchive holds every copy as a printing with its own finish, condition, language and quantity, and prices each one from a nightly Scryfall sync against the right figure for that finish — a foil against the foil price, a reprint against its own. Price snapshots are written when a price actually changes and kept as history, so each card's page charts where it has been rather than only where it is, and the dashboard carries a portfolio trend and a top-movers list built from the same records. A display toggle switches the whole collection between the clean market figure and a condition-adjusted estimate without touching what is stored. See how it works if your current record is a spreadsheet with one stale price column.
FAQ
How often do I need to update prices?
For tracking, less often than people assume. A daily refresh is plenty for a collection you are holding, and the gap between a price from this morning and one from last night is almost never the gap between two decisions.
What matters more than frequency is coverage over time. One reading a day for a year is far more useful than ten readings a day for a week, because the questions worth asking — is this position up or down, which cards moved, did that reprint land — are all answered by the length of the series rather than its resolution.
Should I track condition-adjusted value or market value?
Track the market figure and view the adjusted one. The clean market price per printing and finish is the stable thing to store: it is what the feed publishes, what history is comparable against, and what any future source can be reconciled with.
The condition discount is a display-side estimate, so applying it on the way out lets you see both numbers from one record. Use the market total for tracking movement over time, and the adjusted total when you want a realistic sense of what the collection would fetch.
Why did my collection's value change when no card moved?
Usually because the composition changed rather than the prices. Adding cards, resolving review rows from an import, or correcting a finish or a grade all change the total without any price moving at all.
The other common cause is a printing correction. If a copy was recorded against the wrong printing and you fix it, its price changes to the right one — which can be a large jump on a card with an expensive original and a cheap reprint. That is the total getting more accurate, not less.