That has got to be the most gratifying way to do it (if you like doing things like that) and the way you are most certain to get what you want, but also might get more expensive than buying a complete bike.

Of course, some on this forum seem to have a lot of parts on hand, so for them the expensive way might be to buy complete. And if your hybrid's frame is the wrong size for you, then maybe you don't need much more than a frame that fits and a fork that will accept the tires you want if you can harvest parts from the hybrid.