Digby wrote "I have found nothing to say that Fusilier battalions were any cheaper - or dearer - than musketiers."

I have nothing about specific about fusiliers vs musketeers, but Clausewitz makes the following generalized statement on page 340 of the Howard/Paret edition of ON WAR when comparing the costs of cavalry vs infantry vs artillery:

"There is also the fact that each arm really depends on a different sector of the national economy: infantry on the human population, cavalry on the equine, and artillery on finance... we shall simply make use of the only ascertainable factor: the monetary cost. For our purposes it will suffice to state that, according to common experience, a squadron of 150 horses, a battalion of 800 men, and a battery of eight six-pounders cost approximately the same for equipment and maintenance."

- Ned