I found that a small custom order of aluminized cuben for a tent or bivy would be between $1500 and $4000, depending on the method. 80% of that is "tooling", or set up cost.
Basically all of the aluminized fabrics and films (like space blankets, Hotsac bivys, window film, food packages, etc.)we usually see are made by thermal vapor deposition (which people in the industry tend to just call "metallization"). This method is fast and well suited to large volumes of product. That's how the aluminum was put on the sample pictured in my earlier post.
The other method available is sputtering. Sputtering produces a much more uniform metallic layer that has better adhesion to the film. You can get very durable, mirror-like surfaces with sputtering, but it costs twice as much as standard metallization, and the machines can only handle small pieces that would have to be joined later.
I think Graham mentioned that Cubic Tech has been working on some metallized products, but I haven't looked into it. I think it has potential, too. I was imagining a cuben pyramid tent that was half aluminized, so it could be pitched to give shade, or turned clear-side-east when it's chilly to catch the warm rays of the sun in the morning.