Cattfish I got the tonneau cover aftermarket from a place in Windsor Ontario called Vehicle Ventures. It cost me $1200 Canadian and that included having it shipped, painted, and installed. Oh yeah and that also includes the tax. It's a bit pricey but will last forever. It's steel with a gelcoat and fibreglass reinforcements so it won't warp or crack, and also has a nice smooth surface. Only downside was it took 6 weeks to deliver.
The lid is made by a company called Gemtop, and is called a GT Classic.