Runner looking for a good gym downtown/78704

Hi there, I started running about a year ago and after the austin half I want to focus on building muscle for the next few months. I'm looking for a gym with group classes (don't really know what I'm doing by myself) around downtown or slightly south. I'd like to stay under $100/mo because I'm not rolling in the dough. Not sure if I should go the crossfit route, I'm a bit put off by the culture and the 300 crossfit gyms in town. Yes, i've checked google/yelp but haven't really found anything that fits what I'm looking for. Any advice would be great!