Don't know if I can write the name of another site here, but one that is strictly all about Disney pin trading is having one on Saturday, 9/10 at the All Stars Sports Food Court from 7:00 pm to 11:00 pm to coincide with the Pin Celebration Event taking place that same weekend. There will be alot of pin traders and trading going on, so bring your pins! They also stress on the site that you will need to be considerate of the resort guests and cms and of each other. They will not have exclusive access of the entire dining area, so you will need to mind the diners!
They're a nice group of people - you should have a nice time. If you aren't driving, and not staying at All Star Sports, I would suggest taking a bus directly to the resort from a park or from Downtown Disney. To go back to your resort, you will need to take a bus to Downtown Disney and then switch to your resort bus.
Have fun!