Ask the plumbing contractor if he can provide you a detailed estimate which encloses the price of the fixtures, tools and service charges. This detailed estimate explains why and for what you are paying this amount to the plumbing contractor. You can also judge if the plumber is trustworthy or not with the detailed estimate he provides. It is also not advisable to choose the one who comes up with a lesser amount who may incorporate quality products for fixing your plumbing problems.