If you obtain this type of box, make sure the slot is large enough to put mail through without damaging it. Yes, if cost savings can be demonstrated. For instance, if the carrier will move his vehicle to one location, instead of 12 separate locations. The post office will also take into consideration the distance it must travel to service the box when changing locks. You and your neighbors may jointly purchase a box and install it.
Boxes are available from a number of sources.
A list of approved manufacturers is available from the Los Gatos Post Office. This does not include installation cost. An information packet from the Los Gatos Post Office provides full details. One of the boxes may be used for a locked outgoing mail compartment. Install the box or arrange for a contractor to install the box.