It is simply down to cost. An estate agent has hundreds of For Sale boards produced, either directly or via a specialist company that erects the boards for them. If each one had the price on it then the printer would charge more for printing the boards. This extra cost would be substantial as they offer a discount for ordering large quanitities (like most companies - bulk discount). Somebody has to cover this cost and it would of course be the paying client. Personally I do not believe it offers enough of a benefit to generate higher cost of selling.. . All agents advertise asking prices - in the newspapers or on the internet. So it isn't for any other reason apart from cost.