Fire, it depends on the materials you use. We did a complete bathroom gut job ourselves and spent $5000. But we put in a jetted tub, with travertine tile surround and flooring, and custom cabinetry with granite countertop. After all the work, I can see why labor is so high, it is also faster to have someone else do it.
I have heard that Thomas is on the high side, but I've also heard that they do good work.