$3.50 a pop is not all that bad when you consider that Higher Quality .44 mag ammo costs about $2 a pop. At $5 a pop at family fun days I would consider you a generous fellow.
Imagine how much tool money you could make that day if you really wanted to. I know guys that would probally pay you $10 just to say that they shot the .50
. I have shot just about every common cartridge or owned a gun that shot it except the for the .50BMG. There was a guy in eastern Ohio that was building .50 rifles for a decent price about 5 years ago (about $2000) but I could never come up with the extra cash to be able to justify having him build me one.