How much $ for a plumber near a big city (Washington, DC)?

Seems high to me, too. Who should earn this kind of hourly wage? I certainly did not with degree and 40 years of experience in my field. I think $90-100 per hour is more in line for big city. You were smart to open up the wall. I always advise people to never hire plumber to dig trenches, etc., as you will pay through the nose.