Another vote for Erin at Stable Cloth
I have had several jackets made from her company and they are wonderful. She's great to work with and has a fantastic eye for color. Turn around time is usually pretty quick for a custom--I think my last jacket took 4 weeks.
Hands down the best is Bosley Brangier. Trish is wonderful and their work is phenomenal! I have several jackets and shirts from them and I love them all! Trish travels a lot to shows so you could probably arrange something with her.
Becker Brothers in Lexington KY they are AMAZING. Their main focus is saddleseat attire but their hunt coats are great they even reworked my grand prix's and Ariat hunt coats so they look like customs on me. Awesome to work with and quick turn around time.