Not sure this worth it, look at current storage device pricing and add a higher level Microcontroller to it... NO way you're going to be over the Price of any single Winbond IC... not to mention you can update any part of your firmware and sound using a simple bootloading process.
Requires porting of basic code but take a look at PIC iPod wav player.

Mono CD quality (16bit 44k) for the price of an SD card and holder,
a PIC18F4520, a few resistors for an R2 ladder, an audio amp and a speaker.

Or stereo 8bit 44k if preferred.
Up to 2 Gig's or 512 wav files.


Norm