My sister got her on EBay. There are TONS available. I did mine myself by using thick cardstock and printing them landscape so there were 2 on each page. I cut them in half, rounded the corners (with a corner rounder from Michaels/Hobby Lobby), and I even punched a design into the corners with another punch. They are really cute.

Don't be afraid to DIY. I think mine ended up costing less than $20 to make 200 of them.