plywood and vinyl....
Alot cheaper than buying a ready made one:
The one I made I used foam from Walmart ($5), a piece of vinyl ($3), spray glue ($8), a piece of plywood(free- it was laying around the garage). I cut the plywood to fit-added the fasteners ($2). I sprayglued the foam padding down onto the wood. I used the electric carving knife out of the kitchen to shape the sides of the foam and contour it round the edges.
Tip:
put the vinyl in the dryer for about 5-7 minutes. This will warm it up and make it easier to stretch and wrap around the plywood. You can also use a hair dryer or heatgun when the vinyl cools down to help stretch it around the corners.
staple the vinyl down and you are done.