I have applied the same procedure as described in the N64 Zelda SD Card Reader blog. A Tarus USB 2.0 4-Port hub fits perfectly inside a SNES cart with out having to sand down the molding inside. These hubs can be found for about five bucks on ebay.
There are a plethora of inexpensive usb items with free shipping from all over the world. For the actual game carts a used video game store is the way to go. I just scored a bunch of Odyssey and Atari 2600 carts for about a buck a piece. Perhaps an external hard drive project is due in the coming months! -kaokensho
