Amazon has the well reviewed Creative Labs Nomad MuVo 4 GB MP3 Player for only just over $200.

I'm given to understand that these are quite easilly adaptable, so you can pull out the 4gb drive and use it for something else (here's a link abou how to do so), but for most people, that's not really necessary. Generally, this type of device appears under Windows and OS X as removable storage - hell, it's not even that hard to get at under Linux.

Even if you're not after another MP3 player, this is a good way to get 4 gig of portable storage in a reasonable form factor. And really, who doesn't need more storage?