San Antonio is one of the best markets in the country - I would invest in the area myself. Texas in general has fared very well and our major markets continue to expand and real estate sales have stayed strong.
As for owner financing, you will generally pay more than if you use traditional financing. I would only use that option if your credit is weak or if you can secure a better deal than you can through FHA, VA or conventional financing.
PM me (click on my name and you will see the option) if you have questions about the area or the market and I will be happy to help. It's just down the road from me.
Good luck - and thank you and your family for the sacrifices you make for civilians like me. My mom is a VA nurse, so I am regularly reminded of it and don't say thank you nearly enough
