I have won a few items on auctions (on-line auction houses, gunbroker has different players)
Many ties I have been out-bid on things that made no sense. I knew the value, low and high and have been amazed at what things go for, although like I said, have won some items. Sometimes getting a good deal, other times paying more than I should have.
On gunbroker, I never seem to make a huge amount of money, usually a loss