You might try the history departments at one of the universitys there in Tennessee. Being as it's a Civil War item related to the state the value should be of interest to a collector as well as a historian.
The only source I contacted about it a few years ago was in Georgia. I might contact UT about it and see what they have to say. I took it to my daughter's school one year when they were studying the Civil War and her teacher went nuts. It's always a big hit with visitors. We've had friends visit from up North and they always spend a lot of time in front of that map studying it. It does that to people. :-) It's like stepping back in time.