Sorry for the late reply. This thing they call Christmas ...
Yes, you can add a purchase link to every image, although it is a cumbersome task for 10.000 images of course. I am not sure why you are editing the XML file directly? That is probably what causes the problem.
Not quite sure how or even WHY or HOW you are expecting to add a purchase button for all images in one go. Arent they supposed to go to different URLs as to make them separate? If not, they you shouldnt be using the "puchase" feature at all... You should probably be using the "folderdescription" to add a link that displays for all images in a single folder.
There are full instructions on setting up the [purchase] feature here:
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