Chainsaw Repair

I would get your saw back and tear it apart and post some pics of the piston and cylinder. The cylinder may clean up and all that it would need is a new piston. And to figure out what happen exactly happen to it, lean carb setting, air leak etc.
If your shop is a Stihl dealer they are going to use an oem p and c witch is going to be salty then labor on top of that you won't be far off a new one.