i went for the cheep chinese 5 axis driver kit, i think it was £270 at the time, thats with the power supply and stepper motors included, it was the only part of my build that i was panicking about however i can get 1500mm/m which is plenty for my application (on ballscrews and profiled rails)
im sure jonathan (capitan speed freak) and others will have a diffrent take

i did find the USB option tempting but decided to play it safe and stay OFF the road less traveled :)