I cashiered at the Dollar Tree for a year. People pull the same trick with coloring books and action figures. A week after we go them in, I saw the boxes of Frozen tissues we got going on ebay for 5 and 6 bucks.
I really can't fathom what some sellers are thinking though. I love vintage Disney dolls, and in my saved searches, you can find the same boxed dolls by the same sellers, sitting at a ridiculously high price for YEARS. They're not getting any business and they still feel compelled to do it.