Cheapest procedure for cavities Please Help?

Ok, I recently noticed about 4 of my teeth are loose. All four of my pointy ones are loose, in pain, and seem as if the backside of them are just getting smaller and disappearing. In other words it seems as if I have cavities a lot of them. I'm also having problems with some other teeth. Would it be easier and cheaper to have those four pulled or let them fall out by them selves??? (if pulled around how much money do you think? i live in florida) Would I still be able to eat regular food if I lose those teeth? Also around how much for an amalgam filling if necessary? Can that filling be used for all my teeth or only certain kinds of teeth?