There's a good place in Maldon for Standard colours, or I think Vulcan are good?
I got mine done up in Yorkshire ! (Candy Red) as no one else could do it down our neck of the woods ! Luckily one of the sales reps I work with drives up that way wekly, so no courier costs !
Candy Red cost me £45 (inc preparation etc)
Standard colours from the 2 Essex coaters I called quoted £35 - £40 for a F&F I think, inc. media blasting the frame