You can gain residency if you are in Oklahoma working full-time at least 12 months before school starts. Other than that, you have to marry a state resident.
One of my classmates's wife counts as a state resident since she has met the employment requirement, but he doesn't because he's only been here as a student, so he still is paying out-of-state tuition. He's looking into divorcing and re-marrying his wife (there is a required time period that he'd have to stay divorced) so that he'll qualify for in-state tuition. Considering it'll save him about $20,000/year, you can see why he's looking into this.
Buying a home makes no difference in this policy.
Hope that, along with the previous info posted, helps you out. 🙂