When I did the math on it, I discovered that the cost of raising rodents, and the cost of buying FT from Rodent Pro through the mail, was approximately equal. The only difference is the labor.
However, not all of my animals will eat FT, so I have to raise rodents anyhow. I use both FT and live.

I actually have no idea how much I spend per month...my bad. But it changes every month, anyhow. Right now...not very much, because most of my collection is off feed and in the thick of breeding.