I just converted my G22 to open. Pyramid trigger, zev mag well, carver comp, KKM barrel, stingray c-more mount, c-more sight, extended mag release, and heavy guide rod. Did it all for about a grand. Had the gun already.
Why .40 you ask? The belt, mags, holster is all the same from my limited gun, and I don't have to get involved buying more reloading stuff. I'm going to build a "real" gun next. This was done as an introduction to the class