Average Plumber Yearly Salary in Massachusetts. Plumbers earn a median salary of $63,320 per year.
 Salaries typically start from $35,390 and go up to $116,390.

https://www.indeed.com/salaries/Plumber-Salaries,-Massachusetts

Assume that the work takes 5 weeks, or 1/10 of a year, then the maximum labor costs
for 3 Red Barn Rd plumbing might be $11,639

I would not feel uncomfortable paying twice that $25000.- for labor plus costs of material. 

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The most important task is to establish a amicable relationship;
to https://www.indeed.com/salaries/Plumber-Salaries,-Massachusettsmake the plumber comfortable with the indecency and obscenity
of what he is required to do.