The current in store Purchase With Purchase will be available until April 12.
There is a 20% off Spring sale online and in stores for a variety of items including the limited edition sets that were just released.
The other American Girl sale that has been online for awhile has discounted some of the prices even more.
There is also an American Girl special on Zulily right now.
Also until March 24 you can use the code SPRINGFUN for free shipping on orders over $100 on American Girl's website.