Portable wav player with speed control?

Greetings. I’m looking for an affordable portable or table-top audio player with speed control. I need to be able to slow down the playback to something like 50%. I want to use this to hear certain passages of songs in order to learn to play them. Wav playback is probably better than mp3 for that reason. I can find software (including WMP) that will do this on a PC but I practice in another room and need something portable. Tascam makes a few “trainer” devices (i.e., MP-GT1) built for this purpose but at $200, they’re a little pricey. Creative makes their Zen Stone, but I cannot find anything about it slowing down the playback. Same for Sansa players.

What I need is:
Speed or tempo control without changing the pitch
512MB - 1GB of memory
usb connectivity or SD card
mp3 format at minimum

What I’d like:
CD player
built-in speaker(s)
.wav format files (sound better than mp3 when speed reduced)
continuously repeat a portion of a song

What I don’t need:
video playback
jpg display
wireless network connection
tiny size

I’ve been googling for several evenings now and haven’t found many players that will slow down the tempo of a wav file. Does anyone have or know of a player that will get me at least some of what I’m looking for at under $100?

Thanks for your help.