Ola as Dora would say.
From time to time, Zazzle puts their postage sheets on sale. (Do you get their newsletter? It's worth subscribing, imo) $8 off with the coupon code "AprilPostage" but only until midnight tonight PST.
I have some with artwork on there- http://www.zazzle.com/andymathis*
For comparison, 20 first class stamps would cost $9 at the post office. 20 first class stamps at Zazzle, with the coupon is 11-13 something. So it's a pretty good deal.