What can we find in 2 dollars MP3 Player:

- nice custom package

- graphic lcd (uc1701) 128x64px

- Li-Po battery (I think ~100mAh)

- USB connector

- Jack 3.5mm connector ( Mouser #161-3334-E )

- SD card slot

- on/off switch ( https://www.sparkfun.com/products/10860 )

- membrane keyboard

- asic for mp3 player (I think useless)

For 2 dollars!