Hi, all I would say is for £150 you ain't going to get much of an Alpine. If that's your budget go for a Kenwood, Pioneer or JVC say. Alot more for your money.

£40 is about the going rate if you go to a shop - ask around, someone you know / someone else knows must be able to do it for you. Takes 10 minutes. as long as they have a simple grasp of electronics (which I don't !!) it isn't difficult. Seen it done many times !!!