Older threads turn up some leads (Cantu Tailors, Chris Despos), but those mostly deal with suit alterations and are a year or more old.
I actually live in Arlington, so if any leads point to Southlake/Ft. Worth/etc. those are great as well.
I purchased 4 shirts from them, and I really liked them. I can't remember what book they were from, but they were around $130 each and in solid colors. I think the 6 shirt minimum order involves shirts from another book though.
If I still lived near them, I'd tweak my shirts a bit and order more. Unfortunately, it'll probably be months (if even) before I can get around to returning to Dallas.
If this is your first MTM order, I'd definitely try to read up on all the options you can get though (or just order 1 shirt first).