I bought a used one from a guy on another forum, and I have had a lot of fun with it over the last couple of months. I load 20 g. of FFFg behind a .311 PRB, and talk about knocking the stew out of a tree-rat! For the money, it's the best store-bought shooter that I own.
Haven't had to order any spare parts, so I can't help you there, but I printed a manual from their web-site, and it shouldn't be hard.