After much discussion we have decided not to implement the auction feature.
Reasons are security problems for the site but also legal issues.
Our lawyers advised us that we may be held liable if some people commit fraud during the auction, i.e. collect payments but never ship a product. Sorry for any inconvenience caused, we hope you understand our dilemma. Their legal requirement is that you register, it's free and safe. They have a solid code of ethics and an excellent infrastructure in place. Our webmaster trades there as well under the user name 'franksgarage'.