The plugin is versatile enough to help you hold private auctions for trusted bidders only. When you enable the option to allow only registered users to bid, the plugin will require all bidders to register as “subscribers” (the default lowest denomination allowed by WordPress). You are free to screen them further if you like and remove anyone who you feel does not meet your criteria to bid simply by removing them from the “Users” admin area.
This feature is best utilized for high ticket items or for auctions that require your bidders to be in a certain area. You can combine any other plugin that allows for further registration information and WP Auctions will work just as well.