How much to build a block built shed?

[want2findout]

Can anyone give me an idea as to the cost of building a block built shed (single skin). Internal floor area of 5m x 4m. Will need french doors and one window to front. Standard garden shed roof construction whatever that may be?

We've just had a quote from one builder for �5300 + �800 for the roof!!!

We literally only want someone to do the footings and build the shed. we have a friend who will insulate it for us, do the interior + electrics and will only be charging for materials. We'd initially budgeted �2500 approx for the whole thing?! Aaaarghhhh! is this builder having a laugh or have we completely underestimated the costs involved?!