I own Slabworks Epoxy Floors of Waxahachie, and we're based here and work in many cities around it. Most garages I see have something going on at the surface, like oil spots, an old sealer, peeling paint or cracks. A coating is only as good as the concrete under it, and most of the floor failures I've seen started under the coat, so that's where we spend our time.
The price mostly turns on the size of your garage, how much repair and prep the slab needs, and whether you go with epoxy or polyaspartic. The schedule turns on those same things, plus how long the coating has to cure before a car can roll onto it. When I come out, I'll look at your floor and give you an estimate for your own garage.