That seller used to be really above-board so this is rather sad to hear. They used to sell all antique postcards but the last few years have sold reprints. I don't object to that since most images are out of copyright and this seller always made sure they were noted that they were from a digital collection and were reprints, not originals. It's almost impossible with these old images to tell whether they came from one particular site or the other. I have posted stuff here with the GDE mark and seen them pop up all over the place but I wouldn't know they were mine if I hadn't put the mark on them. Some of these images are just too common--even when they are from the NPG, etc...
Selling other people's original works, however, is a violation of that owner's licensing rights. A complaint could be made to ebay but they almost never follow up on this sort of thing.
