I would call Cincinnati Scuba and Aquatics on Northland Blvd near Forest Park and see if they fill tanks. I know they do all the services for tanks, that would lead me assume they fill them also. Or just start calling scuba shops in the area. Post up with what you find, I’m looking to get a tank soon.
Check with your local fire department as well. They might fill a tank for you. Mine does locally but others have not had luck in this department-seems to depend entirely on the chief of the local department.