Im seeking the best platform to build an ecommerce site that is based around selling photos. My main criteria is watermarking support and a secure file system so that people can url hack and down load the original before buying.

I have tried a few. I was going to build it on a wordpress site, using wp-ecommerce or woocommerce ( what we currently are testing ). Its great I can do everything but handle the watermarking system. The wp-ecom plugin was interesting in the it had an amazon cloud plugin which might be more suited for storing the massive # of 6mb photos we are going to upload as time goes on.

any suggestions as to some options either to move forward from where we are or try something else?