Hatchery with the best deal on straight run chicks?
If you're flexible, keep tabs on Ideal--if you watch their "Advertised Specials" section you will frequently see assortments at a good price.
Meyer has the Leann's "Adopt Me" Bargain. Seems similar to the Cackle Surprise that you can also get turkeys. The chicks are also sold at a per chick price, so you can order 15 or 50.