After allowing myself a bit of a break from plumbing woes, I finally gave in and called the plumbers back out to finish out the job. I picked up all the fixtures and built a small vanity to house the sink (which I finished, of course, about five minutes before the plumbers arrived). The first day went relatively well--the only snafu was that the pipes for the water heater were set too high in the wall (on the day it was originally run, I went to lunch and came back to find them in the wrong spot and the plumber long gone). When it came time to set the fixtures, I removed a small section of drywall, the plumber rerouted the lines and all was fine.

A few days later a crew arrived to run a cold water line from the house to the shop and route the drain line across the back yard. After an hour or so of work and 30 minutes without hearing any machines running, I checked to see what the problem was. As expected: rock. And a big one, right by the shop (meaning that the drain line couldn't be routed around it). They were slated to finish up the job a few days ago, but rain kept them out of the yard. I'm hoping they'll be back sometime this week with a hoe ram. As far as trenching through rock goes, I'm being charged for the rental of the hoe ram and hourly wages for two workers. By my estimation, there's really no limit to what the plumbing could cost.

I'm sure that a year from now I'll be glad that I have water in the shop--assuming (and it may be a sizable assumption) that I have it by then--but right now I'm wishing I'd never called the first plumber. . . not to mention the seventh or eighth. 

The vanity was a quick job built just in the nick of time.
Because the water heater is housed in the shop, I bought a low-boy so I can box it in and use the top as a worksurface.

Seeing no reason to waste space on the bathroom, the sink and toilet take up only four feet of wall space.

Once you hit rock, it's time to call it a day.