The model was put onto a larger card base (it is cast onto a sort of plinth), the edges built up with polyfilla and the basework completed with sand and fence-paint to match my terrain boards. The castle itself was sprayed chocolate brown then drybrushed with a stone-colured paint all over. The walls were washed with a brown/black/pva mix and the roof with a grey/green/pva mix. Total time under an hour (apart from drying time).
Go on, how much do you reckon I paid for it...?
£2. Told you it was a bargain!