Real or Fake AP Royal Oak?

[Schowtyme]

Hi All,

There is a listing for an Audemars Piguet Royal Oak 15500ST on ebay. Unfortunately it doesn't qualify for the ebay authentication check because it had the crystal replaced by a 3rd party. Also, it says it is shipping from Canada but the seller is in Portland. He said he was on a trip when it listed so it showed up there (red flag?).

Please let me know what you all think of the watch, I've asked for a picture of the appraisal he said he got. The seller has 100% feedback but hasn't sold too much lately.

Thanks for your help in advance.