I think I may have stumbled on the problem here. The way the auction works, a person may list his spending limit and have his bid automatically raised
up to that limit if another bid (higher than the one he originally posted)
is made. For example: Bidder A places a bid of $5, with a limit of $500.
Bidder B bids $10, with a limit of $100. Since A's limit is higher, what
shows on the site is a listing that goes from [A:$5] to [A:$105] without
seeing any of B's bids.
Since sellers are complaining about 'people bidding against themselves and
raising the bidding out of reason,' perhaps a bidding history option would
solve this... some way of seeing who is doing the bidding, and who (if
anyone) is bidding more than they are willing to pay.