They are bipolars? I'd use the proper driver electronics for low-resistance bipolars, something like A4988, L6208, or other constant current PWM microstepping control chip - Pololu have a little breakout board for the A4988 for instance: Pololu - A4988 Stepper Motor Driver Carrier
Without the high voltage supply and PWM controller you won't get anything like full speed from the motors and you'll have trouble finding a power supply or H-bridge that works at those low voltages.