KeyRemap4MacBook[1] is free.
Re:From Linux to OSX - 1 Year Later
by chimeracoder on Monday September 10, 2012 @11:18AM
(#4500212)
That doesn't let you remap arbitrary keys; it lets you remap keys in the configurations they've pre-defined for you. That's not the same thing.
Also, the implementation is really wonky, so if you want to do a circular remap (ie, A->B, B->C, C->A), you'll end up with really weird interactions.
It's a stopgap hack at best.
Is the complaint here that Mac OS (any version) isn't Windows?
The alt key on Windows doesn't do the same things the command key does in Mac OS, because they are different operating systems. What an utterly vacuous point.
Not to mention that you can't remap arbitrary keys in OS X without using third-party software, most of which you have to pay for.
Not that I mind paying for software, but I do mind paying for basic functionality that was present in the last version of the OS.