It took me 5 years to build a decent group at a fitness center before venturing out into the world! The fitness center charged a cheap rate for us to train there 4 1/2 hours per week. Once we had our group (myself & 4 other dans) and loyal following of about 10 more, we rented a warehouse, about 300 feet from a busy road. The rent is modest.
There is a community section in our local newspaper that will take almost any community interest stories. (TIP - don't make it look like advertising : disguise it as community news so that it makes the paper)
Next we added a yoga class to help pay the rent. It is really hard to pay the rent & utilities with only aikido students.
I'm sure the San Antonio Express has a community information section. Try that. Lots of luck. I'll look you guys up next time I'm in San Antonio.