Matthew Duclos, if you don’t already read his wordpress, is a smart, well articulated lens nerd and proud of it. Reading his site has heightened my knowledge of glass, both cine and still, at least 10fold.
He runs the family business — Duclos Lenses where they service, modify, and even rehouse all kinds of lenses. Anyhow, the title says it all, and he does an awesome breakdown of why…

http://matthewduclos.wordpress.com/2011/10/07/why-cinema-lenses-cost-so-much/