I got my usb case at wal-mart for $5-6
RIMP
RIMP

I use a Case Logic 6 slot USB Card holder. There are a couple of great pics on the forums here. They can be bought online for about $5 and at Office Max and Office Depot for $7. I keep mine by where I sit and no longer have to worry about the cats knocking all of my stuff all over the place and everything is secure and already packed nice so if I have to leave home for a bit I just zip it and go.