> However, I'm finding several problems. Firstly those microcontrollers seem
> completely unavailable from any shops because they're completely new, also
> they don't have a development kit yet. Another problem will be their
> package, BGA100 and I can't seem to find any applicable adapters for this.
> Any thoughts, comments, answers? Thanks in advance
Are you sure you want to make this? For not too much money you can buy a
complete mp3 player that's likely much smaller that what you can achieve, at
least not for the same money. It will save you a lot of hassle I think.
You can't really mount BGA's yourself, and you need a fine line multilayer
PCB (e.g. expensive) to even get it routed in a reasonable space. Getting
hold of these chips will be difficult, especially as a private person. And
they will be expensive.
Have you looked into the SND1? This one comes in a TQFP144 package I
believe, which is far easier to work with. I have a little player with this
chip and a development kit; though I don't have any experience with it, it's
collecting dust in a box.
The golden days of DIY MP3 players are gone I guess.