Analog Output controller?

Hi guys,

I have 3 of these AMC Servo Amplifiers B30A8:
http://www.a-m-c.com/products/trap.htm

I was wondering, how do I get these to control the motor? I think
they need an analog output controller to send a +/- 10V command
signal, but I'm really in the dark about these things. I've
seen "motion controllers" on ebay, but I'm not sure how I go about
connecting those things to the AMC amplifiers I have. Are there any
relatively inexpensive controllers that I can use with these
amplifiers??

Ideally I'd like to have closed loop, where the computer knows the
position of the motors, but open loop like the stepper systems is
fine too.

Thanks very much!