Hi Matt.
I do not have a positive ID on your guitar but I do have a couple of thoughts. The overall vibe of the guitar seems late 1970's to me. It has several distinctive features that will probably enable you to get a positive ID if you are willing to put in the work. To me, the most distinguishing features are the bullet trussrod nut, lack of a skunk strip on the back of the neck and the tuners.
Bullet trussrod nuts were used by several late 70's Japanese guitar builders and appear on brands like Fresher, Camel etc. Given the combined features of your Strat, my best guess at the moment is that it was built by Chushin Gakki. They built guitars under a variety of brand names and your guitar was distributed by someone that asked them to put Austin on the headstock. Your Austin is a much better guitar than the Chinese guitars currently selling under the Austin brand.
Here are some photos of an El Maya guitar built by Chushin that shares several similarities with your guitar including the bullet trussrod nut, no skunk stripe and tuners. Notice it also has the 2 piece headstock and cream colored pickup covers and knobs with the white selector switch tip. The El Maya logo is also vaguely in the style of your Austin logo.
You did very well for $20, I want to go garage sale shopping with you