I'd give you a couple good sellers on eBay, but i don't think that's allowed. Just check their reviews before you buy.
Also if you're just starting out, trade with cast members, because your "starter" pins won't be anything of value to the die hard collectors that hang around epcot and disney springs. Disney cast members have to accept the trade as long as it's a disney pin and they don't already have the one you're giving in trade on their lanyard.
Google is your friend in this case for more information.
Also, I love to strike up conversation with the cast members if they aren't too busy. Basic stuff like their favorite character, or ride...sometimes relevant to the pins we're trading. Its a really awesome way to talk to people!
