You can also check on https://pure-gas.org/index.jsp?stateprov=TX They show 2 different gulf stations in Houston that supposedly sell pure gas. This site is updated by anyone so accuracy may not be 100%.
BTW The "liner kits" really come in to their own when you have a tank that can't be readily replaced. For instance, there's pretty much zero % chance that I could find a new tank for my antique motorcycle. So once rust becomes an issue with the tank, there's not many financially feasible options other than repairing the one I have some how. So then it becomes a mater of which way do I go, Kreem, POR-15, etc, etc. I went with POR-15, which I think I paid $45 for the kit at the time. Even a used tank for my motorcycle on ebay will typically run around 200, and that's going to be needing a liner and a paint job once I get it.