I've had one friend/neighbor actually by my old 60-in-1 coktail I had. I didn't plan on selling it, but he openly offered an amount(more than what I had into it), I hesitated for a few seconds telling him I wasn't planning on selling it, then he upped his offer another $100. Without hesitating, I shook his hand and said we have a deal. All because his wife was hypnotized playing Galaga on it. If you can get the wife to like, doesn't matter what it costs
And I have made a great friendship when I got rid of my old Omega Race cockpit. Worked out a deal in trade, it helped me out and him out, so well worth it to me.
As for the "posers", I've had a few people at work ask the inevitable "Can you find me _____ game? If so, I'll take it right now!" In my spare time, did some searching, found said games, and they always backed out. One guy I even lined him up on two great deals for pinball machines, talked with him, he said make the arrangements, and then fell through after I stuck my neck out setting up the deal. And then had the balls to ask if I could come take a look at his pin, because something wasn't working right. Needless to say, I tried to help him out and was hung out to dry twice, pin repair from me is NOT in his future, lol.
Anymore, when someone asks about getting/finding a game that's not really into the idea of collecting, I tell them all of the cons that come with it. This way, they stop bugging me, and I don't spend time chasing down machines only to be left holding the bag. Unless they offer to put cash in my hand before I start, I won't even think twice about it. Now if it's for a KLOVer or someone in the collecting community, that's a different story. Others have helped me, I will gladly return the favor and help them.