If you are going to INSIST on it being a Norton, and in good condition and shiny and running,
then thats probably going to mean a 16H Norton, a fine sidevalve slogger if ever there was one.
e.g.http://www.ebay.co.uk/itm/SOLD-1942-NOR ... 1917494064
Lovely olde time chugging power, more like a steam engine in function, as god and JLN intended.
(James Landsdown Norton).
If you are prepared to go for a project, and not necessarily a Norton, then that opens the field wide open.
Bargains galore, if you shop around - but plenty of them are other folks rejects, so shop wisely !!
We could pontificate all day - have a look and see what takes your eye ?
Note too that ebay seems to encourage silly prices, other avenues may mean more sensible prices. (?).
Note also that it is about as expensive to restore the cheapest humblest bike as something more classy,
so don't go totally overboard on something with no resale value !
Or be taken in by someone who has done just that...