And how many botched takes can you afford before the cine lens becomes the overall cheaper solution?
42 is the answer. Now what was the question? Sorry, have read Hitchhiker's Guide to the Galaxy...
Probably much of the cost difference has to do with the exact light transmission calibration, permitting guess-free utterly predictable exposure. Also, it looks solidly built. Just like my old 50 1.4 super takumar! (I've used that thing on my 7D, and it is great!)