I've got a steel frame which was painted by Henderson's Metal Cleaning near Meadowbank:
The finish was very good rather than perfect; turnaround was quick; and the paintwork has been really durable - a million times better than a Bob Jackson paint-job on another bike. I think it was about 70 quid. I'd go back to them again.
Unless your frame is particularly fancy, I think this is the way to go: a workmanlike paint-job and a bike you can ride without being worried about ruining it.