how much does it cost to jack up a house and level it

The cost will most certainly run in thousand dollars. I have seen reports of a $5000 project in CA for a construction company to replace a few piers and level a single story house, and I would say this would be on the lower side. I don't really know how this being in South Texas would affect the price but you really need to have a knowledgeable engineering company to come out to assess the situation first, then give you an estimate. This isn't really a type of a project that anyone can give any estimate worth anything without looking at the house first. Good luck!