Wanted - a Debian handheld

[Richard Owlett <rowlett@cloud85.net>]

I've asked a very similar question on two fora and received useful 
feedback. I've revised my feature list.

Must:
1. be currently available from U.S. retail vendor.
2. have a physical form factor similar to a "smartphone".
3. have provision for using an _optional_ full size keyboard.
   [A permanently attached keyboard is undesirable.]
4. have touchscreen display.
5. be able to read/write a USB flash drive (preferably FAT32 or ext2).
6. not have cell network connectivity as purchased.

Raspberry Pi was suggested on both fora. I investigated it and 
Beaglebone. Both are uncomfortably DIY. Minimally acceptable would be a 
parts list [including case and battery] known to work together.

TIA