James,
I've no idea on cost for these units.....prob stupid money....
but have u considered making ur own.....
Frame can be 150x50x3mm box, easy to get a few plates drilled and welded to ur spec by a local firm if u cant do it.....
a few galv light weight Z section to screw the insulated sides and roof on.....
this way u can customise the size and take it apart/add on if nec....
I do it all the time....
A local fab shop could do it in no time and all u need to do is just bolt it together with a mate.....
ps, inside finish is usually white of cream on the panels....
Plus would u need planning as it's just screwed together.....?
This is my temp cover for machines.....same idea....
once ur kit is made, 2 guys will have it fully assembled in 2 days....
big shed is 7mWx7.5mD....all framework is 150x50x3.....joining plates are 10mm thick....
my new workshop will be made from the same stuff.....I'll just take this apart and reuse.....
my roof sheets were 7.5mLx1mWxwith 40mm insu.....2 men can lift em....
but ur not going that big.....
If time alowed all my frame work would be galved.....whats time....never enough of it....
I'm lucky tho, I can do all this on my own.....heavy stuff the wife helps....hahaha....