I know a really good one in Milton Keynes. Technosound, it's on the Willan Community Center Plaza. I bought all my stuff from there - they are really good! Go to www.technosound.co.uk none of the new products they sell are on their site and they have alot more second hand stuff inside than on their website. They also have a branch in Dunstable (I have never been to that branch, it should be just as good!) Really friendly, non-pushy service. Demos as you snap your fingers.