Ordering a garage door over the phone or online is asking for trouble. Every garage is a little different, and a knowledgeable salesperson will check details like opening size and shape, headroom and side clearance, and even help you make design decisions. And if something does go wrong, there won't be any question about whose fault it is. So make sure you get a salesperson to come to your house and check out the situation before ordering a door. A new 16-ft. door will cost anywhere from $800 to $8,000 and a good salesperson could help you find cheap garage doors.