Well as long as we're talking about USB. Here is a way to get one for a buck (It was free).
Buy.com - Kingston 1GB Data Traveler USB 2.0 Flash Drive - DTI/1GBKR
Cost $11 with free shipping
Use google checkout for the first time and you get $10 off.
Final price = $1 shipped! No rebates, no BS.
If you already used google checkout use a different email and your set.
I did this, they were $10 shipped so you got it for free, but its still a great deal for a buck. I found this on another forum I use and some people got like 5 of them for free. I just did it once.
You can get an SD card for Free.
Buy.com - Kingston 1GB Secure Digital Card (SD) - SD/1GBKR