Here's an example of a closed auction.
http://www.bidgunner.com/auctions/igauer93899389389mm3
Sig Sauer P938
Retail Value: $638.00
Current Price: -$85.73
Placed bids (186): -$93.00
Savings: $459.27
Shipping Cost: $10.00
So the winning bidder really paid $188.73 between the cost of the gun, the cost of their bids, and shipping. If you don't win the auction, you can use the cost of your bids towards the retail price of buying the gun. If you don't buy the gun then it's a good money maker for the website.