You guys ought to find this site interesting.
http://www.handheldmuseum.com/
I once had one of these.
http://www.handheldmuseum.com/Entex/AV.html
Was totally floored to find out it was pretty rare. (I paid less than twenty bucks for it at a Sears Surplus store in the 80's.) Unfortunately, I had to sell it to pay some bills a decade ago.