I wonder just how many of the "high" bids on Gunbroker are legit. You hear stories of people on eBay using a "dummy" account to run up the bid amounts on their auctions. Doesn't seem too far fetched to think someone would use the same tactics on a different auction site.
Plus I've personally seen where someone won an auction with no reserve, only to see the same exact item reposted the next day by the same seller. Now I admit I don't know if the item was reposted because the deal fell through or if there really wasn't a winner, but seeing items reposted like that does make me wonder sometimes, especially after hearing stories about eBay.