Don't get me wrong, the Fast Track is good. The lack of phantom power can be addressed with the Shure PG81 or AKG Perception 150 since these can run off battery (alkaline only please) power. Not sure about the Berrys.
I'm sure you won't go wrong with the Fast Track...specially if you're just recording one instrument. If you intend to overdub a lot... then I'd really, really recommend a Firewire interface instead due to better latency on FW models over USB.
But if you just want a solo instrumental recording type of thing, then the Fast Track is fine... you'll have more budget for a mic as well.
You might wanna look around the classifieds as well, the Firewire Solo and Firewire 410 are very good candidates for your purpose as well, and if you can get it 2nd hand, it would make an even better deal than the Mobile Pre.