it looks like people recommend this for a stepper:
but it's $2.25, and for 10 cents more you get double the stepper control with an Allegro chip (and it does 1/4 microstepping if you want):
http://www.allegromicro.com/Products/Motor-Driver-And-Interface-ICs/Bipolar-Stepper-Motor-Drivers/A3988.aspx