We've had lots of fire ant issues and we've had to use a combination of things to get rid of them. I've had to use poisons because nothing else would work and I had to weigh the risk of the chemicals against the risk of having the kids (including the baby) being bitten and having allergic reactions to the bites and being miserable all the time.
To keep the ants away we use:
-the little white raid traps, the ants usually don't come back out after they come in but sometimes they do; we only have them up on high windowsills (where the ants seem to be coming in) and in other out of reach places
-terro brand baits, they come in an orange box and are liquid and have to be out of reach of the kids as well (like behind heavy furniture); they work really well but have to be changed out every month or so and have to be bought at target (at least around here)
-ortho home defense spray, we spray outside and in the garage, the most important places to spray for us are around the windows and doors where the ants seem to come in, we don't use it inside the house
-professional services, we live on a military base to luckily this is paid for by them so I'm not sure what it would cost but we have had them come a few times to spray around the outside of the house and in the yard (they yard is mostly sand with lots of bugs and it's so hot that the kids never go on the lawn), it helps a lot for several weeks but I don't think what they use is more potent than the ortho spray so I prefer to spot treat with that than have them come in and cover everything with chemicals