That said, the wear on the upper two cogs of the cassette would appear to indicate that bike has at least 500 to 750 miles on it (or at least that cassette does by itself). \
My cassette is much better condition and I got way more miles than that just this year alone and bought the cassette end of last year. And his chain looks more worn than mine as well and my chain is the same one I was using since February, ride all winter. 750 seems low to me.