Hi. I reply to this ticket after a few days, since my last experience with selling pictures uploaded in an event is signficant....
I definitely experienced that people don't buy pictures if they have the chance to download a 1600 px image, in some ways!
So, if event gallery lets people see a 1600 px image on their pc screen, the part of the extension that lets people buy picture is almost useless.... Only people (few ones) unable to do a printscreen, or to perform a download...., buy pictures; or only those who want to print a big size copy of the picture on photographic paper will buy the picture. But most of the people simply want a low/medium resolution picture to share via social network..... or, at least, that's my expereince with windsurfing fans I picture in my photos....
So (consider it a sort of feature wishes....), I'd like that your extension could offer in the future one of these solutions:
1) To let people view only low size previews of pictures on their pc (thumbnails, more or less), and then to let them to buy full/medium size pictures if they want.
2) To let people view only low size previews of pictures on their pc, and then to let only some kind of users (with a paying account) to download/access full/medium size pictures if they want.