The brake fluid flush cost for an average job ranges somewhere between about $89 to more than $130, depending on the type of car and where you take it to get it done. A brake flush procedure is pretty much what it sounds like. Your brake lines are flushed out and new brake fluid is put in. Most mechanics suggest that car and truck owners do a brake fluid flush about every 30,000 miles. It is important to do this so that the brake lines stay clean and help to prevent corrosion and rust that can ruin the brake lines and therefore, cause you to have an accident.