This is going to be real quick. I'm working on adding cart functionality to the site. If I get it to work, you'll still have to bounce over to The Game Crafter to complete the sale, but you can build up your cart on my site.
There appears to be problems with using the ajax/json api with older browsers. I'm not sure they can / it's worth it. to solve them. I may try to detect if they are able to use the site as intended and if not, provide a link to The Game Crafter site so they can buy the games there.