Hi to all,
first of all thank you very much for all the comprehensive feedback. I appreciate it a lot.
As Chicken mentioned, this BoosterPack is not supposed to be used as a regular MP3 player. It's more like a general audio development platform which supported a buch of codecs. For those who are interested to work with audio it can do pretty much everything from simple playback/recording, GUI design to complex signal processing and digital filter design.
The idea came up when I build a Christmas pyramid controller for my dad last year (see here if interested: https://drive.google.com/file/d/0B3L-6crPL7EkQ3lVSEd6cFpLaTQ/view?usp=sharing).
I've created a really nice software package incl. a GUI for the optional display to explore all available functions.
I do realize that the price is a bit high compared to the board found under the links Chicked posted above. I just don't understand how they can sell it which such a low price. The Codec IC is pretty expansive and will still cost $10 in mid qualities (500+) and $15 in low qualities. Adding all the remaining components, PCB and assembly cost the price gets up pretty fast. The only explanation would be they make huge qualities.
Anyway, Yet I made only one prototype board which runs smoothly and delivers crystal clear audio quality. Given the feedback above I don't think it makes sense to produce and sell them. I just can't compete with the price.
Again, thanks a million for all the nice suggestions.