You can get a fill in the blank form and file the petition yourself. Doing that part yourself will save you a ton. I did it years ago. In Collin County its now $299, I believe. They don't take credit cards - cash or check only. The forms are online.
From our experience
Understands Child Support, Spousal Support well.
Understands 'Self employment' situations
Understands trying to get a win-win in difficult circumstances.
Does not bleed the easier situations.