I was once faced with this also. U either get a used unit with unknown condition or recondition the gearbox for the same price.

1 guy i knew said something quite logical. If u recondition the unit, they will replace anything that is damaged, bearings, gear cogs and such. So basically u are getting somewhat a new unit.

With a used unit, u do not know how much wear it does. And its rick factor is far more than the risk of getting a reconditioned one.