Thats good info. I only asked as a unit we've been looking to rent is made from 60mm insulated cladding, it's just short of 10,000sqft and pretty high, I'd guess 25' to the eaves, (we were only looking to take half), and the owner reckons it's cost him £360k to get to the position its at.
From your info buying land and putting a building up isn't so unrealistic
Alex B