Looking for a shopping cart solution for stock photography sales.

Looking for a shopping cart solution for stock photography sales. What I need is the ability to have one ‘product’ with three different variations of differing image sizes. The problem I am running into with Marketpress (and pretty much everything else I am seeing out there) is that each product offers one download. What I need is a product where each variation offers a download.

I was considering doing this in Marketpress, but this would require creating a page for each image (3000 of them) and then creating three products to present on each page (for a grand total of 9000 products).

ANY suggestions, ideas, tips, whatever would be most welcome! And yes, I know this isn’t a WPMU DEV question, but both users and support are so helpful here, I was hoping someone would have a bright idea or have the knowledge I seek!