Fiber is, as runjake mentioned, very very cheap. The raw cost is less than copper, and that is part of why I ran so much of it in my build. (I am not the OP). I did however include some multimode in that equation only because some AV equipment uses is, and not all of them use replaceable optics modules.

I would strongly agree that if you are running fiber, run single mode everywhere. It is amazing how far singlemode fiber can go compared to copper if you are willing to spend money on the endpoints.