I think that the problem is that there are so few 1:6 scale tanks within our price range.
I just go t a 1:6 scale Stuart (plastic: $150.00), but I don't know of any others that are for sale for less than a few
grand.
If you've got the duckies, check out what these cats have to offer:
http://www.totalmodel.com/military/pages/index_19.shtml
http://www.mark-1-tank.co.uk/
http://www.armortek.co.uk/productrange.html
http://www.rcarmory.com/
Jason