Current, non-limted pins can be bought from mailorder at WDW. I don't have the number, but I'm sure someone elses does. The shipping from Disney is high, though, so you're better off ordering several at the same time (save your pennies) to cut the per pin price down a little.
You can always check out the auctions sites, epecially ebay. Some auctions go pretty high, but some are pretty reasonable, and if you check out the gallery portion, it's like your own little catalog to see what the pins look like that are available.
Just to look for/at pin pic, go to Pinpics!
www.pinpics.com. It's a database of over 6000 pins, 99.44% with pics. They have a great search feature to look for a specific pin, character or whatever.
For current pin news and pics, check out Dizpins
www.dizpins.com. They have a daily news update, and get pics of new releases from WDW, DL California and DLTokyo usually the same day they're released. They also have a message board, a trade board and a sale board.
Good luck with your collection.