Coming from the the entertainment side of things, when I first saw this product I was blown away with it, then I was told the price. As far as Projection Screen material goes, this stuff is priced obscenely. Fine for small projects, like the one the OP did, but for anything larger scale, it's just not realistically priced, in my head anyways.
Pat - The Projectors being used for this are just your average LCD/DLP Projector, which can range from $500 to well into the thousands, depending on the resolution, brightness, etc. On top of that, the projectors go through lamps every 2000-5000 hours, and cost between $200-700 to replace. Canon, Epson, and NEC make some very good units.
On the content side, costs really depend on the customers needs, and costs can get out of control quickly. There are a number of companies that can produce content on your behalf, as it's not really a DIY.
On long term installs for products like this, I've found that the problem is that the client gets weary of the on going operating and content creation costs, and lets the install go dark.