Need an ASP.Net eCommerce app that I can make specific changes to (MVC preferred)

I'm planning to set up an online store for a friend, unfortunately his product line introduces some demands most out-of-the-box solutions don't fit. I'm hoping somebody here has had some experiences with an open source package that they can recommend.

The specific issue is that the products are going to number in the hundreds of thousands. Since the type of products have a lot of clearly defined specifics, searching and sorting can be (and needs to be) very granular and efficient. For this reason, the primary requirement is that I replace the product and search-related parts of the app, but only those parts. I'm hoping that there's an ecommerce solution with the product segment abstracted so that I can change the database tables, product display code, search code, and create the obvious code to interact with the database.

I'd prefer something that's built on ASP.Net MVC since it'll play nicely with some extensions I am considering for the future but I'd consider WebForms. I'd also like it to be something that functions on GoDaddy's Hosting, though I'm not optimistic, I just got the account before I discovered how terrible of an ASP.Net web host they are. And finally 开发者_开发知识库I need something that's reasonably mature as I don't have time up front to deal with a system that hasn't been tested, and the majority of issues worked through already.

I'd appreciate any ideas.

Edit: I've done a bit of searching already and I've found several (at least 8) MVC projects, but I haven't had time to examine them properly for the needs listed above. I also can't be sure which ones have matured from real world application...So I'm mostly looking for advice either based on a familiarity with using the app or at least reading enough about it that you would feel it's good to recommend.

Thanks Everybody!

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Check out http://code.google.com/p/sutekishop/

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Check out http://thebeerhouse.codeplex.com/