If you’re free on Wednesday nights, Dr Gary Stier teaches Bagua, Taiji, and Xingyi at Brian Duffy’s Kenpo Karate school (corner of William Cannon & South First) at 8:30 PM. He also teaches privately at his home in Woodcreek (Wimberly), just south of Austin.
There’s also a guy who teaches Yin Style Bagua in Austin, but I don’t know much about him.
I believe there are one or two others as well, if you ask around.