I know someone in the Nashville music scene, I'll ask him the question and get back to you...
Personally I wouldn't spend the big money up front at the demo stage, there are plenty of great producers in smaller studios that can do a great job, I bet there's someone in this forum that'll do you a great demo, top producers in great studios cost really big bucks. Wait until the demo gets some interest, then you might get someone who will want to pay for the Top producer and studio...
Hope this helps
cpm