Your are correct....damn hard to track these things down !!! There are a couple available here on this bidding site
http://www.discount-home-electronics.co.uk/Portabl
e_Television_auctions.shtml
And here's one in the States:
http://www.everythinghome.com/su6cotvcofc1.html
Can't seem to find a retailer here in the U.K. though. They seem to be made only by obscure Japanese electronics companys. The old black and white T.V/Radio/Cassette combos used to be everywhere - my Grand folk always used to have these things the maket must have died out !!