Joshua,
I had termites in my house when I first bought it. It is a single story block ranch on a slab built in 1940. The walls were not insulated and would sweat in the heat, making moisture in the walls (perfect for termites). My wife and I completely gutted it down to the roof joists and replaced the roof, rebuilt the walls, and sealed everything up very well with lots of drylok. We figured we should protect against termites coming back in and got a quote to treat the garage and house. It was something like $1600 and then another $300/year to keep the service "active". We didn't have that in our budget, so we did some research and found bait stations. We bought two packs of these:
http://www.amazon.com/Spectracide-Terminate-Termit...
Seemed to have good reviews, so tried it out. Planted them per the instructions. If there are termites eating the bait, a bright orange indicator will pop into the air. They will eat the poison, and take it back to their colony. It is a slow acting poison, but it will kill the whole colony as they all eat it. Within a week of putting my stakes in, the indicators began popping up. At first, they were clear full of termites. I replaced them over and over and gradually the termites stopped coming around. I haven't seen any termites in them for a few months, so I assume it worked. I will keep more on hand and monitor them occasionally. A problem with this I have found is that other insects (like ants) occasionally get into them and cause the indicator to pop. You can see termites crawling around in the bait station if you lift it out of the hole.
The pro to doing this is obviously the cost and the peace of mind knowing you did it and can monitor it yourself. The con is that you don't get any kind of warranty or anything. I know a lot of the companies will offer something like "if termites damage your house during your pest control contract with us, we'll replace the damage at our cost". You can also get one of the pros to come in and check it out and give you a quote for free. They will let you know if you have termites and what the cost would be for you.