It’s possible things have changed a lot in 5 years, but I’m a Dallasite who moved away in 2010, and before that, I was in a one-bedroom apartment downtown for $500 a month. I don’t know the square footage, but decent-sized, with parking and a laundry room. Groceries and restaurants were cheap too. You definitely had to have a car and put gas in that car, because you drive a lot. But low cost of living. I was making around $30K pretax and pre my portion of the health insurance, taking home around $2000/month, and on that I was comfortably able to support myself and my husband (who was a full-time student) and pay a decent chunk toward my student loans.
Dallas can be very expensive, in that there are a lot of ultrawealthy people and events that cater to them, but you can live a comfortable life on not much. Huge air conditioning bills in summer, though.