A basic package would be the $275 package here, plus a 34V power supply. I believe that all you need for the power supply is a transformer, which is linked on the page. Everything else is included.
A much better package would be this one:
CNC Stepper Motor Kit: , Stepper Motor, Servo Motor, Power Supply Automation Technology Inc
You can expect up to double the performance with this kit. But be aware that the choice of leadscrews can have a big effect on performance.