I did a promo team once; I wasn't too thrilled with the results, the same with buy-in treasuries; you mostly have an audiance from THAT group.
I'm doing a weekly treasury with one of my other teams & that does quite well generatting a lot of outside team views & clicks, although no sales *yet*. Everyweek we pick a challenge (blue treasury, dress treasury, Mad men treasury, etc) and at the end of the week I make a treasury. The most views I've gotten from one is about 150; plus many of them are from people other than fellow team mates. This way, too, you can have a cohesive treasury, rather than some of the promo ones are stuff from anybody and everyone, no rhythem & no theme (mostly), so this way you can have some control over the treasury look :-)