Looking for a .net E-Commerce Application customization

I need to create an ecommerce website(multi store, multi product) using custom developed Ecommerce Application or existing open source project: preferably AspxCommerce or Nopcommerce. (but open to suggestions). There would be little modifications that we may need to do to the open source code. Anyone who has already developed and worked on such a project should only apply. I need to keep the cost of the project at a minimal to begin with and we can expand as the site progresses and we have confidence that the experiment will work. Please PM me cost with a link to a demo along with Admin password for backend, and if the application included source code. You must have demo to show us with back-end admin all ready completed. You need to develop different templates for the opensource project. The page must be able to handle thousands of daily visitors and thousands of productsWebsite should include the following payment methods: Google checkout, paypal, CC Avenue and general.