Not on the website, no.. but the store itself had about ten of them, I simply pulled one off the shelf and bought it. I had gone to the store for another game, but figured I'd just look to see if they had the Maxdrive, and they did.
So the answer is fairly simple.. just go to Best Buy in person and look around.
Bear in mind that MK's program doesn't do all the work for you.. I've yet to create any hybrids of my own with it. And there are processes to follow to get the files to/from the computer, import/export cars/garages, etc. You'll have to put some effort into making it work, and if you're unable to simply go to the store to look for the device you need, then this might not be the way to go for you.