I just bought a RIO Cali 256 from my local
Best Buy for $149.99. Grab it while you can, because it's hard to find an e-tailer with the Cali 256 in stock. Newegg sells the 128 version for $118.00.
I bought the Cali because it satisfied these criteria:
1) Expandable via SD/MMC card. (I have a 512MB card on the way.)
2) Small, rugged design.
3) Good, 18-hour battery life with a AAA battery.
4) FM Tuner
5) RIO is a fairly reputible MP3 player company.
The Cons of the Cali:
1) Requires RIO's software or a plugin for iTunes or WMP to xfer music files (no simple drag & drop).
2) No voice recording feature.
Edit: You might also want to consider the RIO Chiba 256.
$128.00 at Newegg. I decided against the Chiba because its design is not quite as rugged, and I've read reports that its battery cover comes off too easily. Besides case design, the Chiba and Cali are the same.