Welcome to the board!
There are a couple of local mechanics... one is highly recommended and one is highly not recommended. I forget which is which since I've done almost everything myself. There's a stealership in the Corinth area (south of Denton) that is good for mechanic work. I forget the name as it has gone under recent ownership change. The others will chime in with the other mechanic that is recommended.
If you'd like to get a little greasy and do some things yourself, there are plenty of people here that would enjoy doing it as part of an event. Most maintenance items on a Miata are cake to do.
Raymond