Also I can't sell anything on the marketplace for 30 days since I haven't bought anything in a while.

Quote Originally Posted by taggart6 View Post
Okay I think I get it. The system uses the market value to determine card worth and trade value.

Except that Valve takes a percentage of each card trade and that dollar amount is actively removed from the market place with each sell. The trade bot is really just a 1:1 with no overhead cost included.
I think they also change the value based off their own inventory. Bot#1 shows 15c to buy Civ 5 cards, but Bot#2 which has duplicates sells theirs for 10C. I didn't look to see if they are the same cards though. They only give 10C on either bot for the card.