I go into the pricing in a bit more detail in the older post (http://pencerw.com/feed/2015/3/15/3d-printing-titanium-and-t...) but the gist is that 1) the powder is expensive, and 2) the machines are really expensive, and 3) the people who know how to run them are rare and highly prized. Essentially, reducing printing time (by doubling layer thickness) means that you don't need to amortize as much of the cost of the machine during the build.