Everyone nailed it above... my boys are 7 and 5 and love trading. We buy them Disney pin booster packs on eBay, typically for $12-15, and they include 5 pins from a series. They use those to trade. Pins can cost between $8-20+ each in the parks so the booster packs make for a great trading resource. They each now have 2 full lanyards of pins they've traded for. I usually buy a bunch of booster packs on eBay in one shot and then give them as stocking stuffers, Valentine's Day gifts, Easter baskets, etc. This way by the time we go on the trip (we usually go between August-December), they have a bunch to trade! The other thing my wife and I love about the pins is that the boys always want to go to new places like the World Showcase in Epcot to meet new cast members to trade with. This past December was the first time they started trading with other guests, which made me a bit nervous because some people can spot a valuable pin and try to take advantage, but they were very good about saying no thank you when they were asked to trade a pin they had gotten on the trip and didn't want to lose.