Auction Software by its very nature requires an efficient program written in a robust language in order to keep up with all of the inherent automated processes involved. Be aware that there are firms out there selling Auction Software written in languages like Perl or ASP (Active Server Pages using VBScript) that have known problems when used with this type of application. (Google: asp memory leak problems) Ask for ColdFusion, C++ or PHP 5 or above.
TIPS FOR PURCHASING AUCTION SOFTWARE:
Be careful of sites that don't list their phone numbers. That may indicate a one-man operation and poor (or nonexistent) support. Google maps is a good resource! Know who you are buying from. If their address is in a residential area be careful. Ask if you get the source code for the software you are buying. If they say no then you may be in for unexpected charges for bug fixes in the future.