Personally, I'd look for a short sale. Those are houses that are listed below the mortgage amount owed. You can usually do pretty well buying them, and because you're dealing with the owner, you get a property disclosure (unlike with a foreclosed property).
Middle market for rentals in Rockwall is close to $1500 a month plus or minus. So a house for $200k makes a lot of sense. Just find a good neighborhood (Rockwall doesn't really have bad ones). And ask your Realtor to help you locate the ones with good value.
Im not totally sure I understand your question, but right now is a very good time to be buying a house because not only can you get more house for your money but the interest rates are lower than they have ever been. So whether you are planning to live in the home or lease it out, it makes sense. By the way the rental market is very strong so getting it leased shouldn't take ling at all. Just let ne know if I can help.