What a cutie pie!! In a sense, you rescued him. I wish people would not be able to sell puppies/dogs in a flea market situation like that. The new owners have no idea what kind of challenges they just took on, nor how much money they could truly end up spending with vet bills and fighting to get and keep their new pup healthy...
But you got lucky!! I am so happy to hear your story! Welcome to YT, Mike and Baxter!