Op, don't know how important a model 64 in 3 inch is to you but if you look online, you can find model 64 "police trade-ins" in 4 inch for around $300-$350 & model 10s for around $250-$350. Even after you factor in tax + shipping + transfer fee, it should still be less then the $530 he's asking.
3" round butt K frames are hot right now, and for good reason. But, $530.00 for one in the condition described by the O/P is somewhat overpriced. This price is getting into the starting price of 3" model 65's and 2 1/2" model 19/66's.