Affordable place to prepare a will

We are foreigners (on green card) living with our American (+NL/SP) children in Houston. As we are growing increasingly uneasy over the treatment of foreigners in the US and tension with our native countries in Europe, we want to make sure that our family would get our children in case something happens to us. The Texas State ‘taking care of our children’ is my worst nightmare.

What is a place we can get a good but straightforward will in Houston at a reasonable cost?