Don't know if you've already closed this loop, but the Stone Creek apartments in Killeen are probably the nicest/safest in your price range. I had a buddy that lived there for ~4 years and he never had any complaints. Rental houses are usually very sketchy in the area due to the huge population turn-over and the population generally being the dregs of society to begin with.
I heard this week that Child, Youth, and School-Age Services on post is going to be hiring close to 300 people in the next 4-6 months. Jobs are supposed to range from administrative to management to counselors and child-care providers. Worth a look. Go to
www.hood.army.mil and poke around for civilian job opportunities, or search for CYSS in the search box.
Stay away from Killeen north of 190 between post and the Harker Heights shopping center. The odds of your house being burglarized or you being hit by a car in your own driveway are fairly high here. Harker Heights, Nolanville, and western Copperas Cove/Kempner are much more family-friendly, safer, and have less riff-raff than in Killeen.