Sedesma pins (from spain) are actually licensed by Disney and therefore tradable with CM's. I've done it myself.
However, if you're looking for pins just for trading fodder, your best bet is a HECK of a lot of patience with ebay. I've lucked out sometimes searching for pins and finding a bunch by one seller for a buck or two each right before they end. Get then all from a same seller and you ususally get combined shipping. It's not easy to do though and can be very frustrating.
Another option is to do something like hit the
Dizpins boards and post in the for sale board. A lot of times people are willing to sell off trade-legal pins (usually ones that aren't really worth much like open editions and such, but who cares, you're going to trade 'em anyway) for $3 or $4 a pin. Again though, depends on who's got what and who's trying to get rid of what. If you're not picky as to what it is (so long as it's trade legal), then that's how you get better deals.
Trust me though, there are
thousands of people trying to basically do the same thing you are, so unfortunately, it's not easy to do.
-m