Anyhow, great job doing it. Depending of the pricing, I'd surely use it.
I've seen that you make your widget code open source. I guess this handle the flash hack / html5 version for all different versions of browser? Hopefully so because that's the most annoying part of getting the ajax upload working. But then, if that's free, I'd probably take these widgets and just manually code the amazon part.. The only reason I'd use the service is if the pricing is a very little more than what amazon would cost me.
However, that's just for me. Other startups or bigger company might be willing to pay the big price it can save them hours of coding.
And, to everyone you've never done the ajax upload.. trust me that it's a pain. So many browsers and hack.. compressing the images, storing them, limiting the size, etc etc etc. It seems like a trivial task and the first thing you know is that it's been a week you're working on that and then, once you think everything is done, you receive weird message like it doesn't work on IE9 for some reasons, or whatever.