What you are asking for, an inexpensive frequency converter is a contradictions in terms. You would need something that rectifies the incoming 50 hz supply to DC then synthesizes the 60 hz AC from this. In other words a three phase inverter running off a DC power supply or a variable frequency drive running at a constant output frequency; both not inexpensive.
Did you check the motor current and compare it with your breaker rating? The difference in frequency should not make much difference in current draw, and if my understanding is correct increasing the frequency should reduce the current draw because it increase the inductance.
You got it on Ebay; are you sure it is wired correctly and does not have a defect, a shorted winding or something, unrelated to the frequency difference? Check all the windings for resistance leg to leg and leg to ground; I don't know what the values should be but leg to leg they should be the same and leg to ground should have no continuity.