Actually, I've just been reading some very interesting posts on the Agri forum.
People were discussing the possibility of buying a plot and putting a Static Caravan on it, so I decided to have a look at static caravan prices.
You can pick up a decent second hand static caravan ,3 double bedrooms, for as little as £5,000!!!!( - as long as you don't mind how old it is). Then, about £2000 say (-prices vary hugely) to transport it to Corfu.
A potentially very cheap alternative to a new build , plus I don't think you would need planning permission if it was sited on an earth base, rather than concrete.