Taking G7 Spain as a example I would say the costs of its Cavalry have remainded fairly stable even with all the Spanish riding schools and keen interest in horse breeding. Meanwhile the cost to raise a unit of foot has is somewhere between double and triple the base cost and that is with the Spanish taking view that the grenado is a standard bit of kit used by all troops in the taking and more particularly the defence of fortresses so we do not need to copy the Austrian example and have specialist companies.
Artillery costs have also increased sharply and armies these days seem to demand so much more in the way of support functions just to go at the same speed!
However, the real increase in costs seem to have come with Navies! The costs of new Spanish Warships remains a State Secret but the treasury stll says that no war ship needs a Ebony Dance Floor to entertain visitors even if it is the Flag Ship (Cost £10,000 if anyone want one).
At one stage in Gloire du Roi I can re-call every ruler in Glori wanted a Navy and we had the Austrian Marine Corp, The very substantial Prussian yacht Squadron and even the development of a mighty Polish Navy which dominated the Baltic and even helped the Abyssians in the red sea against the mutual Ottoman foe. But with the development of huge up-gunned First Rates loaded with the cutting edge C18 technical developments are players now going "that looks a bit rich" and not looking to develop navies in quite the same way?