Bike looks to be in very, very good condition. I do not see any signs on the drive side of every being laid down. 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). Overall, very nice. Also, signs of some rear derailleur cable stretch as it looks like its been reset a couple times with the sheathing pulling apart. Just my guess...
If I was interested and had any concerns on potential cracks/issues with the frame, I would send the seller a question and ask him if it would be possible to get an inspection of the frame from a bike shop before you finalize payment.
GL - buying used is the way to go. It is how I got both my R3 and P2 at close to 30 cents on the dollar of the going rate when they were new.