stepper motor power issues...

I have a pair of unipolar stepper motors that I am trying to drive
with a combination of a PIC16F877 and ULN2003A. My code and
connections seem to be fine, but I am having trouble finding a power
supply/voltage regulator combination that has enough juice to power
both motors. Any suggestions? I thought each motor needed 2Amps, but
it is clearly using more than that because it works when only one is
going but not two. If I assume that they are actually 4amps each
instead of 4 amps total, then how could I get 5volts, 8.5amps (I have
a few other parts drawing a small amount of current)? I don't want to
spend a fortune but I am willing to buy some parts if need be.
.

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