http://www.GeodesicSolutions.com - I use their classified script at
http://www.VintageRadio.com. The auction script is in the mid $$$ but their software is very good, easy to use, and is well supported. The only problem may be getting people to use your auction or classifieds site. I have a lot of traffic but few people place ads even though that is what is on most of the front page. The internet is one big city and its mostly an ebay/CraigsList sort of world, unfortunately. People seem to be VERY set in their ways.
http://www.webidsupport.com/ looks like a great free program. I'd vote for Geodesic over iLance though in the paid category, I think. Still, the problem above exists but I might try the freebie for something as an experiment with auctions (at least its free - No money made but no money lost at the worst!).