Stepper motor voltage VS amps.

I am looking and making a small 3 axis CNC mill for wood routing and
such. I have been surfing through Ebay and it's endless supply of
varied stepper motors. The question I have is this. I see several
postings that say for the power source to use 20-25 times the motors
rated voltage. So if the motor says 2V you should use 40-50V. I
understand this is done for responce and such but what about the
amperage? If it says 2V 3A should you supply 40-50 Volts and 3 amps?
Or do you supply it the same wattage as the motor plate adds up to?
2V x 3A = 6Watts. This seems to low.

If any one can shed some light on this subject for me I would greatly
appreciate it.

Thanks
Scott