Metzee has no valuation feature. No price guide, no estimate, nothing telling you what a thing should fetch. Anyone claiming otherwise is selling something.
What there is: four ways to get close, and one number that outranks all of them.
The number that outranks them
What it is worth to you. Not the market — you.
An auction finds what two people will pay. If that is more than your number, you let it go. If it is less, you have done well. Market value is useful context and it is not the decision. How to not get carried away
Four ways to get close
1. What the same thing has gone for. The best signal there is, and it is ordinary homework rather than a feature. For anything you buy repeatedly, keep a note — three results are worth more than any guide.
2. The condition, specifically. Most apparently-wrong prices are a condition misunderstanding: two items identical in a photograph and two grades apart in the hand. Ask before you value. What do NM, VG and the rest mean?
3. What came with it. Box, papers, certificate, receipt. On collectibles the difference between with and without is often large, and it is the thing people forget to ask about. What is provenance?
4. Whether it is graded. A sealed, graded item is a different thing from a raw one — somebody independent staked their name on the condition. What is professional grading?
What not to use
The start price. It is a hook, not a valuation. A low start is a seller trying to get bidding moving, and a high one is not evidence either. What is a reserve price?
One past result. A quiet night with two people is not a market. Three results are a pattern.
What the seller says it is worth. Not dishonesty — everyone values their own things generously.
For anything expensive or frequently faked
Get an opinion from somebody who handles these, before you bid rather than after. A museum, a specialist dealer or an auction house will often look at photographs for nothing.
And for anything inherited, slow down entirely. I inherited a collection — where do I start?
What protects you if you get it wrong
Not much, and that is honest: paying too much is not a fault you can raise. What you are protected against is the item not being what was described, which is a different thing and is covered for 7 days whatever the store's policy says. What if the seller lied about the item?
So the research is yours to do, and the description is theirs to get right.
More: how do I know the price is fair, how to not get carried away, five questions worth asking before you bid.