Changing a flange is a routine task for professional plumbers and will cost you about $175. This price can vary depending on the type of flange being replaced, the severity of any damage to the existing flange, and the location of your home or business.
Plumbers typically charge by the hour for this sort of work, so a more complex or time-consuming job will usually cost more than a routine repair that can be done quickly.
Regardless of price, it is always best to hire a reputable professional to ensure the job is completed correctly and that you receive good value for money.