So... I bought a Memory Card Plus from Estarland.com
I have 2 Sega direct-save mem carts I bought in Japan some years ago. I might be willing to let one go... It will need to be formatted and you shouldn't let it sit for too long or it may lose save data. They need to be plugged in and used every now and then. I tend not to use it because my AR is always plugged into my Sat.