Ya' know, a 150 dollar PDA with wi-fi, running freeware, can act as a streaming audio player, and can play all day long if connected to an AC adapter. Plus when you unplug it, it can do much more.
My Dell Axim X51v is a higher end device (than the 150 dollars one would pay for a Palm-type device), but I use it often for internet radio. I can even connect it to my HD Radio, and using the free Windows Media Encoder, can stream HD stations not on the 'net so I can listen to them anywhere with a wi-fi connection.
Something I would consider before spending hundreds for a "one-trick pony" device (that could ONLY stream audio and/or video in a fixed location). Hell, using Orb, I can stream VIDEO as well as audio from my home system to anywhere I may be!