The clearbra is not an BMW OEM offering. The few stealers that sell clearbra's are probably farming the work out to local installers who either cut their own plastic or buy the pieces from aftermarket sellers.

I'm getting my clearbra done by a guy who designs and installs vinyl decals for on vehicle advertisements. He bought a CD package containing all of the cutting templates for all popular cars; he cuts the pieces on his vinyl cutter which runs off his computer. Therefore, he didn't carry an inventory of clearbras, but instead cut the plastic as needed for each contracted installation. He's no longer doing clearbras, he now does advertisements on buses, taxis, and vans, but he's coming out of retirement to do mine.

From what I've been able to detemine, the material costs are pretty much the same from installer to installer - it comes down to labor costs.