Bill..............I have a good buddy who has his own powdercoating shop. Have helped him now and then over the years.
What you want done can be done but it would be expensive because of the time involved taping off the other ares to put the red on. The shop you talked to was right........get them done in black and then do the red in paint. If the raised lettering is coated with powder, just sand them to scuff the area for the paint to better adhere.