Jesse,
You'd like to stay away from the areas where the churches are you will be working with (to live). I'd say to look around in Los restauradores, el Milloncito, el Rosmil. usd600 is a low for a house with a small garden. If you are coming with some kind of missionary organization, they might have the correct connections to get you an appropriate place to live for a reasonable price. I'll send you my email to your pm.