It is unlikely that I'll ever pay $200 for a chip, but if I did:

I would be absolutely certain that I got what I paid for.

I would not hesitste a moment in demanding a refund if I felt the product was not as advertised.

I would not be intimidated by the seller's status/reputation.

It is obvius from your post that you KNOW you've been ripped. No arbitration or grading is needed. Get in his face NOW.