Are you sure you want to handle it that way? Once your customer clicks onto Amazon you've lost them. You may get the affiliate sale, but I'd think you'd be better off keeping him on your site.
Try embedding an Amazon aStore in your site instead. You get the Amazon cart, checkout, etc without leaving your site.
For instance, I've got a site that has no real direction at the moment and is serving as more of a sandbox than anything. Check out
DonkaTa: Tool Store to see what I mean about embedding an Amazon aStore.
FULL DISCLOSURE - THIS LINK IS AN AMAZON AFFILIATE LINK. I'M ONLY SUPPLYING THIS TO ILLUSTRATE A POINT, NOT TO GENERATE SALES.