Jeff, there has never been a more opportune time than right now (if you have the means). I'm not sure of why some of the bigger names failed (most likely it was not the right time). Some are still making a valiant effort, but I don't see them going anywhere.
Auctiva certainly has the branding at this point. If the means are within reach, the only other thing you need is a good ad campaign and good employees to make it work.
Sellers are more than ready to make a switch, the buyers will follow if they know where the sellers are.