I will get blasted for this, I'm sure, but if you're only going to trade them away, go ahead and buy on eBay and don't worry about if they're "real". Most of what you'll find on the CMs will be exactly the same. So it's crazy to spend Disney size prices for pins to trade away for ones people got from eBay. If you're doing it as a value investment, this is not the way to go. But if you're doing it for fun, to trade, to collect, to find ones you like, for your DD to get every princess one she can, who cares if they're "real". And despite what people here will say, 99% of people can't tell the difference anyway! They'll claim because it's stamped correctly, it's "real". They're just as likely scrappers.
I buy the big lots on eBay for my boys to trade with. Then while we're on the trip, they get to pick out a couple special ones at the stores down there. Those are NOT for trading! Those are ones that represent a favorite ride, the year we went, a favorite character, etc. Those are ones they keep and display at home. But for the ones they're trading, they couldn't care less if it's a $10 pin or a $1 pin. They just like it and that's all that matters.