IMHO I think you would be poorly advised to use a simulator for this purpose. Due to the highly simplistic way in which the rotor/aircraft aerodynamics have to be modelled for real-time simulations correlation with the true behaviour can be poor. Therefore, you will find significant differences between the simulated behaviour and the behaviour of the real machine.
I think you would be better off spending your money on the real thing.
NOTE: There are many areas of helicopter training, in which the use of a simulator would be a valuable aid to training, but I don't think autorotations is one of them.
CRAN
PS: If you are looking for an R22 simulator, the only one that I know of is Prof. Gareth Padfield's at Liverpool university. I believe one of the helicopter operators at Liverpool airport has a contract to carry out flight training in it.