I never had any interest in pin trading, but DH started getting excited about it last summer. I followed him around and stood in the background while he scoured all the CM's vests and lanyards...
Then one day, I saw a Chip n' Dale pin I just had to have. So I traded for it and...voila! I was HOOKED. We spent soooooo much money on pins last summer, it's no wonder we practically starved!
But seriously, it's so easy to get started. Just buy some Disney pins to start with (make sure they're ones you don't want to keep, though!) Then start looking at CMs' lanyards or vests...they're more than happy to let you browse...and if you see one you want, offer to trade. The CM will not say no, I guarantee you.
Once you get started, you won't be able to stop! Have fun!