I guess depends on what you want to do with it, show, drive, pose, camp etc etc.
I would not be in a mad rush until you did a lot of research as nothing worse than buying something then hating it later. Millwebs is most likely a good start http://www.milweb.co.uk/home.php as you can look the classified then also find a list of dealers.
Then in here to research it and ask about it. Ask Jack for some Pathfinder magazines
My fav's.... A Schwimmerwagon are quite pricey but nice from the Axis side. Big a Scammel recovery truck. The Sexton would be interesting. Lots of variety, spend a month in this madhouse and you discover new vehicles all the time that you never heard of before
Also depends if you want a complex rebuild or something easy. For me a challenge is all part of the fun.