Reverse auctions are the opposite of a standard auction. The auction starts at a price around the market price as a buy it now auction, and the price is dropped every 1-3 days. You decide when to purchase, just don't wait too long or you might end up missing out! Bookmark this page and check back often to see how much the card has dropped in price and what new reverse auctions are launched. Good luck!
Update August 21st
The current reverse auction is listed below. The new reverse auction is a 2008 Allen & Ginter Bruce Jenner SP Autographed card.