Sorry if I seem a bit harsh here but there is no way I would pay you anything to do your first trigger job on MY gun. I also work on computers, computers are plug and play, replace broken components, etc. No "smithing" involved. Matter of fact, I won't let the local "gunsmith" touch my gun (sorry Bubba), but I'm less than 100 miles to Cylinder & Slide.
I may back off my assessment if you can list here both the steps and the tools (Brownell cat. numbers a bonus) to do a trigger job on an M&P9.
Work on your own guns if you must but from the perspective of liability alone I would not touch another person's pistol without training, tools and insurance (that's why a smith charges so much, not because he can but because he must, to stay in business).
I do work on my own guns, doing a sight swap and Wolfe spring swap on my Sig Sauer P6 this week, but that's a far cry from a "trigger job".