Is your time worth basically zero?
To properly powdercoat those parts you'd have to disassemble the gun, paint strip the parts, clean them, powdercoat them, bake them, clean the powder gun before and after use to purge the colors, reassemble the gun.
You're going to price yourself out of your own market soon when you realize that you can't pay the bills at that kind of price, for the amount of time it takes to do it PROPERLY.
I see this venture not lasting long, if you're willing to work for sub minimum wage. That, or you have a lower standard of living than I do.