The OnSemi D-STPR-GEVK stepper motor evaluation shield is on sale at Arrow for $6.20, compared to over 50 bucks at Digikey and Mouser. This shield will drive two stepper motors.
Technical documentation for the evaluation board seems scant with a brief search, but it shouldn't be too difficult to figure out.
I'm pretty happy of what I got for my 6 bucks. Not only a dual stepper motor driver but a nice stepper motor too.
[Edit – the board IS AN ARDUINO SHIELD – disregard the next paragraph.]
I thought this board was an Arduino shield but I was mistaken – it's an expansion card for an OnSemi dev kit. Not quite plug&play but very useful nevertheless. It will just take a little effort to figure out the interface to use it with any micro.