When looking for saws and parts, it's always a crap shoot on Ebay and CL. At least with CL, you can look at the stuff first and bargain with them on the spot. I think that usually on Ebay you wind up paying market prices, or more for saws. There are deals, but they are few and far between. Parts are a good deal, and it is probably the best place to sell, as someone else mentioned. If you want a project or hobby saw, then CL can be the best bet, and then Ebay for parts.
We are lucky around here in that there are a few really good shops that cater to loggers, and the prices and service are very hard to beat. New Stihls and Huskys are usually cheaper than the best stuff you find on Ebay. If you need something new and/or dead reliable, you buy from them. Also, there are plenty of higher quality used saws in the area too. For example, the 372 I just got on CL was bought new and used by a guy to clear his 5 acre rec property. After that, it had just been sitting in his garage. Then again, if you see a saw for sale in a known "logging town", there's a good chance it has been really beat and has high mileage.
Lastly, I've also had good experience with a couple of the supporting vendors here on AS buying parts and accessories.