My friend (based in Church Crookham) does it on the side and I think charges around £300 for prewash, wash, clay, correction, wax and sealant. You'd have to check with him about exact details, e.g. if it's a 1/2 stage correction etc... but I know he's meticulous and takes a lot of pride in what he does.
Let me know if you want me to send over his contact details so you can ask questions etc...