RCA Jet Stream - They're maddeningly opaque about what standard they're using, but the Jet's big feature is that it works with a pair of wireless headphones that they're promising will "seamlessly deliver crystal clear music". The splash-resistant player, which has 1.5-inch OLED display, an FM tuner, and 1GB of storage capacity, 12 hours of battery life, and also comes with a stopwatch and a body mass index calculator. MSRP is $149.
RCA Jet - This one is pretty much just a wired version of the Jet, with a 1GB version selling for $69 and a 2GB version going for $89. Guess removing the wireless headphones stuff shaves a more than 50% off the price.
The RCA Opal - The big selling point of the Opal is that it can double as a digital photo viewer (which, honestly isn't all that novel of a feature by now). That is, assuming you don't mind looking at JPEGs on a 1.5-inch OLED screen. Battery life is rated at 15 hours, MSRP is $79.
RCA Pearl - Heading up the low-end is the new budget RCA Pearl. The Pearl has a microSD card slot for adding storage, a built-in digital voice recorder, and support for playback of MP3, WMA, and protected WMA (they don't get specific, but do mention that it'll work with "most Internet download services"). Gets 15 hours of life on a single AAA, retail price is $49.