Don't buy a Superdrive without confirming that it will work with your Mac. I quote from a recent post by David Empson in Usenet:
1. Without modifying either OS X or the hardware in the drive, it can
only be used on Macs which were supplied by Apple without a built-in
optical drive (with one exception - some Mac Mini generations where
there was a mixture of models with and without optical drives).
In particular, you can't use it on a Mac where you had removed the
optical drive to install another hard drive, nor on one where the
built-in optical drive has died in some way, nor on a non-Mac.
2. It needs more than 500 mA from the USB port, so even if you make a
modification to get around the host model check, it will still only work
when plugged directly into a built-in USB port on a Mac which is able to
recognise Apple peripherals and supply more than 500 mA on request,
which was a new feature in most Mac models from Mid 2007 (the Mac Mini
didn't get that feature until Early 2009).
(My emphasis.) I can't answer for the accuracy of all this, but obviously you should bear it in mind.