Mastering is definitely its own animal.
However, this is on its way to the mac in the not-to-distant future...
http://www.har-bal.com/
...and it's less than $100 (at least the current PC version is).
Too good to be true? Maybe, but I've seen dicussion of it elsewhere and a lot of people say that it does do what it claims. I contacted Har-Bal a couple months ago and they said that they are currently working on the mac version... no timeframe though.
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c