I did my garage in Vegas with epoxy myself. I used the Behr Single Stage Epoxy, Behr Wet Look for my clear, a whole bunch of metallic flake. I acid cross etched, and rinsed like a mofo. I'd say after chemicals, paint, flake, clear and tape, all tools including a scrub brush and a sprayer to spread the clear, it was right around $500.00 for me to do it myself. Now I wasn't doing a garage that same size as you. So I'd expect a bit more, probably around $800.00 ish. all depends on what you have available. I had nothing paint related so I was literally starting from scratch.