Its a lot less expensive outside the London area. Yes you might pay £250 and more at the likes of White Waltham, Redhill, Shoreham and even more at Fairoaks, but get 100 miles north or west of London and its much cheaper. More like £100 per month or less. Of course it depends if you are in a nice hangar with lots of space, or all jamed into a big hangar that leaks...