A couple years ago, I helped a girl get into a laptop computer bundled up with Reason and a couple MIDI controllers so she could practice all the neat new stuff I was introducing her to.
She bought an Axiom 61 (to use at her apartment), and also a Roland Edirol PCR-M1 ($150) which tucked nice and neatly into her bookbag where she could go to any restaurant with her headphones and make music while drinking coffee.
Well, she LOVES her Edirol, but I see now that I think it has been discontinued. Too bad! The newer versions are big and clunky, like the Axioms.
Here's the link for it on Roland's site. Be sure to look through all the images so you can see how sleek, lightweight, and portable it was. Maybe you can find one on Ebay or a music store with one left in stock. Good luck!
http://www.roland.com/products/en/PCR-M1/