I spent about $25 to build an organizer for the trunk of my 2006 Honda Civic EX. Check the specs...
The Trunk Organizer. Features include skateboard racks for two boards, top shelf and changeable dividers. All components can be removed or manipulated slots and Velcro attachments.
The grain of black-stained cedar, the most lightweight wood. The top shelf provides an additional nine inches of storage space above the trunk floor (eleven inches).
The organizer weighs only 20 pounds without the skateboards.
Velcro dividers allow manipulation with ease.
Rear complete with cooler for food and drinks. It is the main storage area, providing the full 19 inches of trunk height. Seat drop-down lock (only accessible from inside trunk) are rigged to allow interior access but can be switched back with precious cargo.