As still photographer's we're spoiled. Or idea of an expensive lens is $6,000 and if you look around for used you can cut that by a third.
Then in video, cinema, motion, whatever you want to call it, starting entry for a PL mount lens is 5 grand, a zoom is twenty thousand, a fast zoom (T 2.2) thirty thousand and that's for non powered zooms.
Like CB we've tested a lot of lenses and like CB some you can see a difference, some you can't, though motion can be more demanding on the physical attributes of the lenses, a little less demanding on sharpness.
Since I have two RED's my thought was to usually have two sets of lens mounts. 1 with a nikon mount for single operator, fast shooting, where the focus is pulled by the operator, the second PL mount where we hire a focus puller and they handle it.
First we tested the Zeiss Mini Primes in PL mount that were sharp though slower than their ZF (nikon mount) lenses and a little slower so we went with a series of the ZF Ziess to go along with a large set of older Nikor manual lenses that are sharp but obviously still lenses so the barrel focus is a little sloppier and not as tight or accurate as the Zeiss.
Now we are buying RED PL mount primes because the price is good, the lenses are fast T 1.9 and the primes are very sharp, though I thought the RED zooms were less sharp than the primes. They are not as well built as some other lenses, but since we own them they'll get much less abuse than rental lenses.
For zooms the only time we go to a zoom is when we hire our Steadicam operator and focus puller that works off a remote. They prefer the Agenieux zooms which is a beautiful lens and allows for fast shooting as you don't have to change focus attachments everytime you change focal length.
I thought of buying one though the entry is $20,000 for a T 2.8, $30,000 for a T 2.2 which makes rental a little better idea than buying, at least at the moment.
We have stayed away from the Canon servo lenses for most uses (unless we use a 5d2) just because there is non focus stops on the lenses which makes focusing to marks impossible.
The Canon lenses are sharp, though nothing we've tested is sharper than the Zeiss lenses in any mount.
Nothing is as pretty as the Angeniux.