We were quoted 5k for a kid's bath, which included replacing tub, changing out a window, replacing toilet, redoing tile on floors and in tub/shower, and installing new shower/tub fixtures.
SO, my dh watched youtube and we did the entire thing ourselves. For about $2,500, we did all of the above (had tub reglazed vs replacing) plus replaced the 72' countertop, painted the cabinets, replaced the mirrors, lights, a couple of doors in the bathroom that were warped from moisture, new sinks and faucets and replaced the medicine cabinet.
We were told our master bath would be about 15k with materials. We need to have some plumbing moved in there and my dh does not want to do that so we will most likely contract out some pieces of that project but still try to do most ourselves.