I'm looking for a portable hard-disk MP3 player that I can use whilst I'm
out and about, and also something I can easily use in the car - is there
such a machine and what's it likely to cost?

I have a Ford 5000 head unit with a boot changer that I want to retain, so
there must be a way of keeping both the MP3 player & the boot changer -
probably some way of switching between the two as I only have one aux
connection.

Any advise and costs most gratefully appreciated.
Cheers