if you are not worried about absolute correct maps,look around for 1/35 scale maps, altough I have used 1/48 or 1/72 scale maps as well, it was a bundle from Verlinden I picked up cheap from ebay.
They look like a map which is to me the most inportant and when folded up you only see a tiny portion so it is hard to say where it is from.
just my 2 cents.