I live in Houston, Texas and if one visits the Painted Churches in the Schulenberg area on one's own, there are no charges. Now...if one is going on a group tour, then you would obviously have to check with the specific tour group as to any charges. Perhaps they charge for gasoline or to pay the driver, etc.
Sorry that I cannot be more specific but hope that this helps. There are some Painted Churches probably closer to your part of the State.