Bridges are not available to replace all of your teeth. Bridges generally are cheaper than implants. As far as cost is concerned, you would have to consult with dentists local to your area. The prices can differ greatly from area to area, state to state. It also depends on whether a general dentist is doing the work or a specialist.
There is also a type of denture available that "locks in" to the jaw. Screws are placed into the jawbone, much like implants, and the denture locks into these screws.
You really need to consult with a dentist and have a treatment plan worked out. From there, you can consult other dentists for a second opinion and/or inquire with your insurance company on what is covered and what will not be covered and at what amounts. You will also be able to compare prices with other dentists once you know exactly what it is that you need.