If you really want to improve the bidding process, here is something to help the sellers. If the seller has a auto-accept percentage set, why not alert the bidders when they offer less than the auto accept price giving them the option to purchase the card(s) immediately at the auto accept price?
Also why not put some time constraint on offer retractions? Even if it is only an hour it can only help.
Buying Brandon Hughes (OSU/Chargers) Auto's and low numbered cards.