Unfortunately, I didn't read this other ripoffreport about shopgoodwill.com before bidding on an item sold through the Tacoma, WA store.
My item appears to have been bid up by a shill bidder. I won the auction at exactly my proxy bid, i.e. the highest price I was willing to pay, and the auction was bid up in the last few seconds by a user name that I had seen bid on items from that store before.
Of course, I can't prove that the users is not legitimate, but it was not a username that had bid on the item before, and they managed to stop just at my proxy price so that they didn't actually win the auction.