AutomationDirect.com has a 10A 80V driver for about $260 but the voltage is too low. Read on...
You probably want to run any stepper at a much higher voltage to overcome the stepping rate limitations caused by the winding inductance. The current rise time limits the steps/second - substantially!
According to the article, you might want to run the motor at 10x to 24x nameplate voltage or somewhere around 480V to 1152V. At these voltages, winding insulation quality will be a huge issue.
http://www.e-jpc.com/blog/?p=111If you don't need RPMs, maybe you can get by with something more conventional - like 80V.
What happened to the original driver?