Rarely will used saws like that be as much of a 'deal' as you hope. Many will get run up to within $100-$150 of a new saw. Then you get it and the bar is bent or not the size you want, and the sprocket is original. By the time you buy a bar, chain, sprocket, air filter and whatever else, you are within $50 of a new saw. And for a $50 discount you got some saw that was beat to death and abused for 6 months, run on God knows what fuel mix and run hot how many times???
Nope, for $50 difference I'll buy a new saw.