Hi Dragonlight,
People rave about RANT. I've only used it briefly, but I believe it's the only affordable sim to simulate ADF dip (a characteristic of the ADF causing the needle to "dip" when turning towards the beacon, for example).
I mainly used MS Flight Sim X at home. I found the handling aspect rubbish, but you can stick the autopilot on and then place yourself in "random" positions around an NDB hold and then figure out the best way to enter and subsequently remain in the hold. You can pick it up (a new copy) for less than £20 these days. Defo worth it IMHO. I'm not sure if you can get one that is compatible with Mac.
Good luck!