Harbor Freight is an excellent choice for fastening in the form of Haul-Master's Ratcheting Tie Downs. These thick nylon cords are designed to hold up to 400 pounds in place without ripping or tearing ...
This allows you to move bigger objects, and you can pick up the Haul-Master truck bed extender from Harbor Freight for $59.99 -- which happens to be a great store to find additional truck bed ...