@Matt Riley There's a lot of good advice in this thread. I've lived in Austin my whole life and it's been awesome to see the change and growth of all the zip codes and surrounding towns. My girlfriend and I are currently looking to do another hack in the same price range (250K-350K). If I'm being honest, we are pretty much priced out of East Austin proper in that price range (78702, 78721, 78723) unless we are willing to do some renovations. My girlfriend hacked her house in Southeast Austin (78741) and has had success with that.
Much like other Realtors here, I like 78753, 78754, 78758, 78759 - close to the Domain, Apple campus, Samsung campus, the new Austin FC stadium - these zips are and will be growing for many years to come. South Austin is great too (78741, 78745, 78748, 78749). 78744 has great prices and is super close to the airport, Mckinney Falls, and has easy access to most anything if you're willing to drive. However, it is a bit of a food & entertainment desert out there - nothing really exciting in that zip code unless you drive across 35 or into downtown/East Austin. Fortunately, they are breaking ground on a new development just east of the airport in 2021!
As far as towns around Austin the obvious choices are up north - Round Rock, Leander, etc. I love Pflugerville for it's population growth (~100%) and median income (~70K), and the houses are super affordable and EASY to hack.
If you're interested in taking your hack a step further, I have helped several friends build a tiny home in their backyard for less than 40K. They rent it out as an Airbnb and earn between 1500-2500 per month. They are able to live for free and earn some serious cashflow with that short-term rental.
Best of luck!
Jeremy Vandermause | Shaffer Properties