Cutting patch cables to length

Having made up far more cables than I care to think about I'm going to suggest option C as your best bet. I personally would make up my own cables and have done so before but I can assure you that when you're talking about a rack worth of cables it really is a tedious job at the very best of times and downright torture for anyone not well experienced at it.

The fact that you're asking the question at all hints to me that you haven't made up a great many cables yourself, as you appear to be unaware of the amount of work involved. Figure a cable per minute at the start (if you are quick at it) and a cable every couple of minutes after the first hundred or so, because you slow down when the fingers get tired and cramped. To do the job well every cable also needs to be properly tested, which will take say another half a minute or more. Now figure out how much time that's going to take you for the whole job, at the end of which you'll almost certainly be cursing your decision to take that route.

I would say that what you're looking for is very uncommon. People who do this sort of thing for a living (data cablers) would go through hundreds of feet of cable a week, in all the colours of the rainbow, and so buying by the giant spool is no problem for them. People who don't do this for a living typically aren't good enough to do a couple of hundred crimps reliably and quickly enough to make it worthwhile.

I buy cables pre-made in the appropriate lengths needed, then just take up the small amount of remaining slack in neatly cable-tied "zigzag" routing on the side of the rack. Does the job nicely, you just need to invest in massive numbers of cable ties.