Of course ebay is a good source, if you pay attention to feed back and buy from reputable sellers. However newspapers and local want ads can turn up gems too. As far as what to look for, a 60" saw is going to be 100cc at least. You can google "chain saw collectors corner"to check model # with size. As for parts, unless you have developed some good sources then you should look at the larger companies like homelite or mcculloch along with stihl and husqvarna as parts will likley be plentiful pretty far back for the more common models. Unless you are already brand-loyal try to be open minded as far as brand. That way you won't miss out on a cool find. Just watch the auctions on ebay for a while and see wich saws are more common and what stuff is going for. Educate yourself first with these coupla things and it will help.