Final Fantasy Hacktics

The only requirement for a magic memory stick is that it is "magic gate enabled," and less than 4 GB (technically you CAN turn a 4GB+ mem stick into a magic memory stick, but it is a real pain).  I used a San Disk 2GB mem stick for my first magic memory stick because that was the most economical one at best buy at the moment.  

Also note that turning a memory stick into a magic memory stick is NOT permanent.  When I did it, I backed up the saves on my memory stick, made it magical, hacked my PSP, then I formated it and put the saves back on.  You only need a dedicated magic memory stick if you plan on doing a lot of customizing to the PSP's firmware (which you don't have to do for FFT patching).