If you want a
small, portable, battery-powered terminal, get an HPLX
 palmtop (95, 100 or 200). Runs for weeks or months on two AA batteries.
 The HPLX palmtops  have a VT100 emulation. I have not had a need to use
 it, but Tony has and perhaps can comment on its fidelity to the real
 thing. 
 Yeah, except they are ridiculously expensive... If you can get your hands on
 an android device w/ a decent keyboard for $60 new IMHO you are much better
 off than w/ an HPLX. Plus you have much more options as far as SW and
 functionality goes. 
 
It's $30 more than your android device -- I don't know if that falls
into the category of "ridiculously expensive" or not.? I see them sell
between $50 and $125 fairly regularly.
- Josh