$150 is OK.

it depends on situation as well. Sometimes if you have to cut and solder pipes, doing special wiring, $150 is not much. :)

Yes, haul away is important.

When I do mine, it would cost an hour or so, but usually stressed by two lines: hot water in, and dirty water out. You need to follow your local code as well, such has the high-loop of waste line.

The power and the injection to dispensor or the air cap might be tricky.