I'm an ameteur.I do not have to think in terms of a business plan,and there may be a better way.
I have had excellent luck with Cylinder and Slide hammer/sear/disconnect kits,of the service to carry sort vs competition.
For myself,I have the Wilson beavertail jig and I like their grip safety.
Look at Fusion Firearms kits
I built one on a Caspian frame/slide.Good stuff.
Frankly,for a modest investment,you can get a slide/frame/bbl from Sarco,RIA,for about $225.IMO,its good value,and servicable.Maybe a good learning project.
I lean toward Ed Brown or Wilson for the rest of my parts.
Get a high quality slide stop.
I like the basic Colt thumb safety.Buy two.They are under $20,the first one might be practice.