I had not read anything about fusilier regiments being cheaper. However, I do remember reading in several sources that fusiliers were originally raised for the specific purpose of guarding powder trains and the artillery trains (which also had large stocks of powder). Being specially armed with the then-new flintlock fusils instead of the commonly used matchlocks, they were considered better for this security role. It has always been my impression that the new fusils would have cost more than matchlocks, being new and bought in fewer numbers. Perhaps I am mistaken in that, though a I can also envision a tightfisted government calculating to make up for the expense of the weapons by paying the soldier who carried it less money. This all, of course, took place in the 17th Century was pretty much irrelevant or even forgotten by our period.

Robert A. Mosher
The Military Philosopher
http://militaryphilosopher.blogspot.com/