2000 Chevy Monte Carlo Coolant Leaking

I have been fixing several problems lately with my car, including new tie rods and new tires. My car has been leaking coolant for a while, but its always been at a slow and steady pace, having to refill maybe once every month or two. I've already replaced the water pump, and that seemed to slow it down, but lately its picked back up and is now much worse than before. There is a small puddle of fluid in the passengers side floor and every time I stop there is steam venting out from under my hood and the car smells of engine coolant every time I turn the heat on. What is going on with my car and, if you can tell me, what is a reasonable price to fix it?