Assuming its for the MK4 Escort, without the rear skirted? bumper. Expect to pay up to and beyond £100 for new or near as new set.

The rears are designed to fit the rear bumper as per the moulding on the flaps.

You can fit the front flaps on the rear bumper to save yourself a few quid.

Also in order to fit them you'll need the clamps (3 per flap) still available from Ford and a self tapping screw for the rears aswell.