So, after having spent some time with the beta, and also seeing Youtuber's play with it as well, I feel like making stuff more expensive, although works for buildings seems like a sort "artificial" way, for lack of a better term, for making it more difficult to get powerful and elite large armies.
So to remedy this, I think CA should look into putting caps on elite units. These caps could then be further expanded through buildings and technologies. Meaning that in order to field a lot of your best units, you have to invest heavily in them. instead of just building something and calling it a day. I don't know about everyone else, but currently one thing that takes me out of the immersion of the setting and makes the game seem rather stale in the later stages is just fighting massive armies of nothing but elite troops, with armies of nothing but elite troops. Like armies of Greatswords, Blackguards, Iron Breakers etc. etc. I think finding a good limit system would help keep that from occurring at least into farther into the game, as well as making those elite units feel more distinct and enjoyable, and make you feel as a player more satisfied with your investment in them, also giving you incentive to keep them alive.
I feel like this would be a great way, that not only would help balance this issue, BUT also allow for the opportunity to put in more interesting technologies or at the very least modify ones that already exist.