Best trade: I gave a Champ Groove to a lake. In exchange, I got water immunity on that course for 1 year from the Lady of the Lake.
Worst trade: I gave an old acquaintance (we used to disc together frequently) a pearly Pro Line Spider in exchange for a future trade (I didn't throw it and he loved Spiders). We fell out of touch, he forgot, and now I see him semi regularly at a local course. He still throws it, and made it a point to tell me so, but seems to have forgotten about our agreement. I don't miss it, so I never brought it up.
Another guy, I sold a MachLite to for $100 in payments. Got $50, then $25, then nothing. Again, I didn't mention it to him since I only paid $20 for it and came out ahead. He went through some tough financial times before his last payment, so I let it go.