I guess I'll jump in here with my stories, both positive and negative. As for the negative, I ran into these "collectors". They need a hard to find part for this old saw they just have to get going again, usually with a family history or trying to get it going for a down on their luck friend. Then when you see it on eBay, or another forum classified, it just ticks you off, and makes you skeptical of anyone else that comes along.
On the positive side, there used to be a dealer near me that would call me when he needed something. more common stuff, I'd just sell or trade to him, but one day he needed a plastic flywheel fan for a 70E. I had a couple in my private stash, and wasn't sure what to do, so I asked him who it was for. He told me who it was and it was a guy I knew. He used to deliver grain when I worked on my cousins farm and was just the nicest guy you could know. He had bought the saw new from this dealer and was probably close to 80 at this point and was still putting up his wood with the 70. I said, "if it's for Glen, I have one" and we worked out some trade.
And there are a few people I've met through the forums that have helped me out. Robin sent me a couple of handguards for some 49/52 years ago, and Bob has helped me out several times (I even got a 930 part or two out of him). But I consider these guys friends and no saw is worth losing that.