Not sure if this is useful, but for $30 and free shipping you get a 3.5 inch composite display (only 960 x 240 pixels) in an enclosure, a 2200 maH built-in rechargeable Li-ion battery with 12 volt, 500 ma output through an auxiliary power jack (in addition to powering the display internally), a video input cable with a yellow RCA plug for the Pi's composite output jack, an audio speaker for mono audio input (e.g., from the Pi's stereo output), a 5-volt AC-powered charger/supply, and ... a Velcro forearm strap!
http://www.ebay.com/itm/Portable-3-5-TF ... 4173186c4a
The best things in life aren't things ... but, a Pi comes pretty darned close!
"Education is not the filling of a pail, but the lighting of a fire." -- W.B. Yeats
In theory, theory & practice are the same - in practice, they aren't!!!