NEXT STEP. Find out how much your project will cost. Provide a few details about your project and receive competitive quotes from local pros. The average national cost to clean ducts & vents is $333, with most homeowners spending between $238 and $429.This data is based on actual project costs as reported by HomeAdvisor members.EXT STEP. Find out how much your project will cost. Provide a few details about your project and receive competitive quotes from local pros. The average national cost to clean ducts & vents is $333, with most homeowners spending between $238 and $429.