Most are for under 5's is there a reason why you don't want a wooden one?
this \link{http://www.diy.com/diy/jsp/bq/nav/nav.jsp?action=detail&fh_secondid=6690006&fh_reftheme=promo_52578109%2cseeall%2c%2f%2fcatalog01%2fen_GB%2fcategories%3c8530340&fh_start_index=20&fh_location=%2f%2fcatalog01%2fen_GB%2fcategories%3c%7b8530340%7d%2fcategories%3c%7b8530359%7d&fh_eds=%c3%9f&fh_refview=lister&ts=1147639764795\B&Q} looks quite cute
I know you can find them less than £200. Look \link[http://www.outdoortoysdirect.co.uk/Childrens-Wooden-Playhouse/Waltons-Poppy-Playhouse\poppy playhouse} here. This is cheaper than plastic ones!