When I saw here some recommended prices in the under $500 range, I have to remind myself about last year when a logger friend ran over his MS661 with his truck. The saw was in shambles. He asked me to restore it and I agreed to try. Parts alone cost over $500. After 10 hours of work, I got it running like the day he bought it. Yes, it was a gamble, but he figured it was worth it, and the saw runs today.
I suppose we are comparing apples with oranges, but a fine-running Stihl saw should be worth close to what it cost to buy it because (1) Stihl raises their prices every year, and (2) inflation of the dollar tends to cancel out equipment depreciation. At least that's what the forum used to say 10 years ago.