Ecommerce - advanced customization and features

Building a site like mixed with features from [login to view URL] and [login to view URL] The number of products displayed can dynamically change [login to view URL] It will be a feature by feature match of those two sites. There will be an auction system like [login to view URL] with a stores feature for the sellers. The credit card info will be automatically charged using [login to view URL] The best bidders will have tons of Ecommerce experience, the ability to handle such complex features, and great feedback. You also have to convince me that the cart you plan on using is the best cart to use, and why.. In Pm's send me complex ecommerce experience. If you dont have feedback here send links to other feedback or references. I like Oscommerce but am not stuck on it.