I was looking for something similar a few weeks ago. I will give it another try.
I need something similar to spreadshirt.net. I need the product design and shopping cart/order part (no affiliate or other stuff).
I need to be able to populate the shop with different products (not only t-shirts). And I need to be able to set the available options for each individual product type.
I need it to be built in ASP or ASP.NET and probably flash for the design part. No PHP solutions are interesting.
I am looking for a prebuilt solution where I can se a fully working demo before I place an order (not only a screenshot).