About a million of them mate. 99% of flash MP3 players can be used as a drive. google is your friend.
I'd go with the Creative MuVo Micro N200 or V200. The V200 is hard to find but actually has a standard USB port, the V200 is smaller but requires a cable. Both are available in 256, 512, and 1gb versions. They have radio and a voice recorder. I ordered the N200 512mb yesterday for $125. Plus, it's just a little bigger than 2 AA batteries put side by side.
I dont know what kinda capacity you're looking for but I got an ACER USB memory stick, 128mb, with Mp3 mode for £30 this Xmas. Obviously its no iPod but for £30 its hardly got a huge price tag. Simple and does the job of giving me something to listen to on the way to college
Aria do 512 Mb mp3 players for about £50 IIRC http://www.aria.co.uk/productsList.asp?Category=42&Submit=submit