I'm assuming this is a working saw, so taking that in to consideration you will most likely being looking at $500+ dollars. For this kind of money I would definitely do the following:
1) Remove the muffler and inspect the piston for scoring.
2) If you have the ability I would highly recommend a pressure/vacuum check of the saw.
3) Test the compression of the saw warmed up.
4) check the clutch for over heating. The drum or the clutch itself will look blueish in color. Also, massive browning on the plastics around the brake.
Other things I consider in the price.
1) Does it need fuel and impulse lines. Mainly look for cracking.
2) Filters, air and fuel
3) Spark plug.
4) Does the carb need rebuilt?
5) Condition of the bar, chain(s), and sprocket.
6) broken plastics and handles?
I personally believe the above maintenance items also show you how well the saw was taking care as well.
In a nutshell be careful because a bad saw can be made to run well for a few minutes. Good luck.