Nice I know it will be a bit of a drive but Cedar Ridge has Steel challenge competitions on the 2nd and 4th Saturdays of each month in Bulverde. I've taken my kids a couple of times and it's been a good experience.
As far as competitive teams for the kids, depending on what your looking for there should be plenty. For the kids I know there is a team out of Dripping Springs, my boys are on a team based in San Antonio (Twisted Ballistics).