There is a bloke selling one online for beer money.

I think he doesn't know what it is.

So how do Electones/Stageas etc compare to digital pianos?

Other than a helluva lot more controls

Aren`t they electronic organs, popular in the 70`s? Some people liked `em . . . .

There's really no comparison, because they are a completely different type of instrument. A digital piano is just that, a keyboard designed to digitally simulate a piano. Electone is a line of Yamaha electronic organs, though many of them are designed with much more than organ sounds -- you can find videos on YouTube of people playing them as a one-man orchestra. Here are a couple of impressive examples:

http://www.youtube.com/watch?v=8i2rsMfMvIw

http://www.youtube.com/watch?v=ictDaIzDj8Y (I think this latter one is an Electone -- if not, it's the same concept)

So, comparing a Yamaha Electone to a digital piano of any model (even one with hundreds of instrument sounds, a sequencer and other extra features) is like comparing apples to oranges. I've never played an Electone myself, though being an organist as well as a pianist I'd love to get a hold of one and see what I could do with it.