I only collect, but hubby likes to trade. After kinda sorta being "taken" for an AP Dining pin series pin (he had NO idea that they were coveted, but he really loves the pin he got, so it's 49% "taken" and 51% happy with it for him...for me it's 99% negative but it WAS his pin) he really only trades with CMs. If we're in a store and the CM is willing to trade, he'll look at their pins. He doesn't really do it with anyone else, now.
The serious traders LOVE one of his pins, and he's asked to trade for it several times a trip. He knows better...before our big '07 trip, I bought DS and DH some pins that were from my heart. Two Cars pins for DS b/c he was really into Cars. A Mr Incredible pin for hubby b/c he was working SO SO SO hard for us to be able to afford that trip. And a special ying yang Hong Kong CM pin, b/c hubby is Korean and lived in Hong Kong. That's the pin that is very much wanted by traders. I think people drool over it!
We too buy the "mini allen wrench" pin backs.