This Media Player

NewEgg.com has the Griffin Technology iKaraoke iPod Microphone for $18 + $5 shipping = $23 shipped.

Product description from NewEgg.com:

iKaraoke\’s all-in-one microphone/processor isolates the lead vocal track, then fades it, giving your voice room to make that favorite tune yours.

Don\’t keep that raw talent hidden. Plug in or use iKaraoke\’s FM transmitter to play through your home or auto stereo. Use the mic to!
control the music, volume and reverb. It\’s your tunes as only you can sing them.

The lights go down. The crowd goes wild. You know you\’re a star. iKaraoke proves it to the world.

Product link.