I buy a ton of parts, shop supplies and such on Amazon. Prime shipping is great, and most times, especially on a hard to find part, is faster than the stealership. As far as returns go, I've really only had to return a couple of parts, but the process was easy, quick and painless both times. They shipped out a replacement part, packed with an RMP and I shipped the wrong/defective part back in the same box! I once returned a hard to find a/c compressor because the customer bailed on the job. They accepted the return, no questions asked and I got a full refund. So far, I can't report a negative experience with Amazon. As far as profit goes, I tend to pass the savings down the line to my customers. I meet my margins just fine and everybody wins.