Three For One Sale on Exit Signs.

OK, lets do the math.

1 staircase, about 15 feet long
3 exit signs installed about 12 feet in the air in a place that can't really be seen except by crouching down at the bottom of the staircase. (note the difficult photographic angle)
6 emergency lights, approximately 600 watts of power
1 open exit plainly visible
Countless hours of labor to install all the signs.

Found at the 86th street and lexington ave, number 6 train.