Have a look at my build thread - Meet poppy. Midland paintwerks did the work on my bus.
http://forum.earlybay.com/viewtopic.php?f=2&t=42741" onclick="window.open(this.href);return false;
You should be able to get a quote for painting, its all the additional work that no one will quote for until they have seen you bus.
But I would be put aside at least half of the above upper figure for what ifs. also decide if you want the engine bay, interior, bumpers and wheels painted as this will all add to the cost.
Also dont be tempted by the cheepest price, look at the reviews etc. Lots of cow boys out there. Also dont pick one because they are local, MPW are about 200 miles from me and I would recommend themin a heart beat.
Do it right, do it once ;-)
PM me if you havbe any specific questions you would like answered.