I know that to mention Chinese stuff is frowned upon, but it is not all bad. There are some nice driver boards using the new Toshiba 6600 chip with a large 2" x 2-14" X 5/8" heat sink, and they are rated at 4.5 amp, 48v. They have settable amps, and up to 16 micro-steps, and cost about $28.00 each for a single axis driver. Look on Ebay. http://www.ebay.com/itm/New-Product-4-5A-TB6600-stepper-motor-driver-board-/290901201259

John

I'd rather spend a little more and buy 4 of these:

http://www.amazon.com/gp/aw/d/B00DFSF9GE/ref=ox_sc_act_image_1?ie=UTF8&psc=1&smid=A10EAPE4CAYC9P