Great info from jasons there. I went through this turning a DAO (not DAK) P226 into a DA/SA. The internals ran around $60 from Midway, and while the hammer was quoted as a special order with some crazy lead time I had it within a week or so anyway. (I needed grips as well, but found some used Hogues for like $5.)
Well worth doing, imho. There are a lot of beater ex-police DAO P226s out there with, uh, "challenged" cosmetics and pristine internals, and with mine I think I'm still under half the cost of new.