From what I understood looking at everything made for cinema, they're pretending to sell everything at 10-50 times more their price just because they think every person working for cinema is freaking rich.
Just think: how much would ever cost to produce such lenses? Think also at the other Canon Cinema Zoom Lenses with astronomical pricing, think at the bolts and knobs (which are just plain stupid pieces of metal) made by RED as accessories for their rigs, they're as expensive as if they were made out of solid gold...well they aren't!
At this point I really wonder how do these lenses compare with the new Samyang T1.5 35mm AS UMC, Samyang T1.5 24mm ED AS IF UMC, and Samyang T3.1 14mm ED AS IF UMC which cost a fraction of that price (about $400-500), and we all know how spectacular is both the build and optical quality of Samyang lenses.
As far as I know, cinema lenses have a different set of requirements, which makes development/manufacturing more expensive. Examples are the lens being parfocal and not having focus breathing.
You can read more here:http://www.lensrentals.com/blog/2011/06/photo-lenses-for-video-there-is-no-free-lunch
I don't know if you also pay a premium just for the "cinema" tag in the name, but I don't think that would be the only reason for the significantly higher prices.