Hey Zio, does that Champion pump have the optional 'Low Oil Shutdown' switch?
If so, first check the oil level, if it's good, turn the white knob clockwise a quarter turn and see if she'll run. If not, bypass the switch and try again.
May even be something as simple as the overload on the magnetic starter needs to be reset. Get your multi tester out and be sure you're getting power to the motor side of the coil.
Baldor motors are pretty bulletproof. If the motor was constantly run underpowered (low voltage) it probably burnt out the capacitors, which are easy to change out.
Personally, I'd be burning rubber to give the seller $150!! Go for it.
Good luck,
Tom