Ah-ha! Good point on price levels, they appear to be static (no overt deflation/inflation). The problem lies in estimating a value for the market capitalization rate to be used in the DCF analysis. A lot of assumptions would have to be made but you might be able to infer a rate based on the cost of mercenaries. You pay mercenaries an initial cash sum plus a periodic "rental" rate. The rental rate obviously incorporates army size and composition, but you are also paying the mercenaries for their time. Mercenaries get paid whether they are fighting or just standing. A fact I forget sometimes with bad results.
You could calculate some general "average" that would help solve the question: if given $xxx.xx gold for one period, what is the equivalent in generic "troops" I could have mobilized instead? I know there is a hidden rate relationship somewhere in there because, if you remember, the mercenary rates actually change over the course of the game. While I don't think the stated up-front amounts change, I know the number of mercenaries in the units increases as the game goes on. Ceterius paribus, the cost of a single mercenary decreases as the game progresses. For example, the White company starts with like 4k troops and ends the game with like 10k troops.