I got some done at Advance Litho in Baltimore. That was about 20 years ago, though. There was a graphics shop on St. Paul Street near Mt. Vernon, Alpha Graphics, I think it was called, that also did them. Not sure if either is still around. They're very durable, I'm still using the ones I got all those years ago... As I recall, they weren't terribly expensive, either. I took them the artwork and they did the rest.
The large "LAUREL VALLEY" and the car number are from that set, I did this car about three years ago. The other markings are from various Micro Scale decal sheets.
Lee