Pin trading is so much fun! We did it for the first time on our last trip this past Feb. I bought a lot from a man trying to raise money for his daughter's school trip on ebay and I got some GREAT pins- I had several that I chose to keep just for sentimental value. Both our boys (Ages 7y and 2y) got into it. ODS got into searching for pirate and Star Wars pins and the little one just wanted to do whatever Big was doing, but still likes to look at his pins.
Everyone here has posted good information about how trading works, how to start etc. I just wanted to say that we loved talking to the CM's and even other guests. One little girl (maybe 5yo) saw dh's lanyard and was telling him how much she loved Rex from TS (he had a Rex pin) and how much she wanted a pin of him- she told him she would trade him one of her favorites for it. He told her she didn't have to do that, but she insisted- she was so cute!
Have fun!