Looks like single phase to me with that huge junction box on the motor. The big wire brings the power to the motor, the smaller wire brings the on/off signal to the starter on the wall. I'd say that's an excellent price for this unit if it is not in need of work. Even if it was, it would probably still be worth it.
Can someone give me a clue to what size this tank is? I assumed it wass 80 gal but seems bigger .