If you are looking for a price to epoxy the floor as well, there are too many variables to just state how much it costs. Depending on your area of the country, pricing for a contractor can start around $4 a square foot and go up from there for a basic once coat each of primer, color, and top coat system. Even then it depends on what kind of product he is using.
If you are going to do it yourself the same factors apply. How many coats, what kind of product, paint chips or no paints chips, and etc.
This a great forum with lots of great information from people who have done their own floors as well as representatives of different products to answer your questions. Just take some time to do some research on what you think you would like for an epoxy floor covering and then you can probably narrow down a more accurate idea of what your costs would be.
Good luck!