The answer to 'cost to replace roof vent' is that the typical cost to replace a roof vent can vary widely depending on several factors. The size and type of vent, the complexity of the installation, and your local labor rates can all impact the final price.
Generally, you can expect to pay anywhere from $150 to $500 to have a roof vent replaced by a professional roofing contractor. Simpler vent replacements on the lower end of that range, while more complex jobs with custom vents or difficult access could be on the higher end. It's best to get 2-3 local quotes to understand the typical costs in your area.