The data we have is far from only ebay.
The higher the values, the less data and more discrepancy there will be. Fact of life for any catalog and you cant expect to trade on that basis when higher value chips are involved.
Lets change your scenario:
You swear by James' book prices which suggest a fair trade of your chip X for 10 of my chip Y
I go by the Chip Rack which suggests a fair trade for your chip X is 5 of my Y
What happens next?
