Well come to the pin trading boards...I can't believe no one has answered your request...so here goes...
1. you can trade on these boards here and at DL or WDW.
2.You can buy pins at WDW, DL or check out Dizpins they have a board where people sell pins or you can check out others sites that sell pins there, or go to ebay auctions.
3.If you want to trade online, I would make sure the people you are trading with have references or if you feel uncomfortable ask for someone to be the go between. Most people are really great...and personally I've never had a problem but I don't do the volume that a lot of people do.
4. Pins at WDW, DL are anywhere from 6$ , 8.50 and up...the hard to acquire pins can cost big$$$$$$!
5. Anyones guess is as good as mine but pins have been around for a while...I started collecting Olympic pins for the LA O. way back when....Disney says it is at their discretion when they will stop the program...I think it is so big right now I can't see them stopping in the near future.
6. A pin Primer...you can go to Dizpins...they have archives that show what has come out...Pinpics has a list of all Disney pins right now...great site!
(those are the 2 others that I frequent)
7. these opinions are the sole opinion of Holycow and I can not be held accountable for any inaccuracy of this information...
8. Buy some pins and start trading!
Good luck!
Holycow