I bought 110 pins for my kids and another 50 for a friend. It took me 6 months to accumulate them.
I look for sets or lots of 10 or under. I search the seller and if I see several lots from them that are identical I stay away my theory being that there will be a flood of those pins and they will be harder to trade. ie the "incredibles" pins that people were saying were everywhere. I also search thru all the auctions, again looking for "multiples" I try to find the different and unusual.
Read the sellers feedback.
I like the CM lanyard pins although they are fairly small. I have won several lots of them.
I usually pay $3-3.25 per pin, I don't want the cheapest ones out there. I also look for the LE pins, those are the ones I really like to get.
Last night I was sorting thru the pins for the kids to wrap for Christmas. I had no duplicates and a great assortment. I think they will have a blast with the trading. They started to get into it on our last trip, so this time I wanted to be prepared.
While wrapping, I actually pulled out 4 that I want for my lanyard, guess I will have to negotiate a trade with my kids.
I love the pin trading, it is a great way to meet the CM's. They come from all over the world and some have some really fascinating stories to tell.
To those questions I read:
Green Lanyards are only traded with kids under 12.
CM's are not supposed to trade for a pin they already have.
If it says Disney on the back, they are obligated to trade it.