I lived in Brighton up until last year - and if I used to use Smiths Coating in Hove - £40 per paintjob, whether that be frame, or frame/bars/forks etc - if ir was one colour youd pay for one powdercoat session. Good results too -
however you have to strip and prep the frame first - I used to take mine to Chris Smith Restorations - who do blasting etc.
Having said that, I then discovered Superbikedan on here. For the price of sending the frame to him, him then stripping, prepping and painting, then return post - it worked out about the same price as having it prepped and painted in brighton - and the finish was 50 million times better. Smiths coatings are good, but Dan is the master. SO send it to dan! [or go local, no worries!]