On the Smallest levels it's you buy some Disneypins and trade them with the CM's This is very fun for the Kids .
On the larger levels it's a collectors dream with big pin trading events and limited edition pins of all kinds.
Check out my DD's Tink room in my SIG and it has a picture of her keepers hanging on a curtian.Most were traded some bought because she really wanted that one.
We started buying the cheapest on-sight pins and trying to trade up.Then we went to buying pin-lots on E-bay (have to watch what you buy)and trading them.