I'm running a special on two of my bid directories: 4yn.com safaari.com SPECIAL: Submit your url and place a bid and we'll match your bid and double you up! So if you bid $10, you'll show as a $20 bid.
That would really suck for any previous bidder that bid $19 or less. For a mere ten bucks, I'd jump ahead of them. If I was a previous bidder, I'd be pissed. It's no wonder bid directories get a bad name.
It was called "a special" for a reason. Have you ever purchased anything that went on sale a week later? This doesn't stop stores from offering a "sale", does it?