Dean, any art store will have them.
Curves or at least the right type of curve is critical. That has to be right or it is just not there.
For instance, look at Kenneth's picture of the bowies that he posted up. Now, mine is the right top. See the curve of the bottom of the handle from mid handle to back. It is off. I never said I was smart so some of this takes time to soak into my head. That was the best I could do at the time, However now I would either use a different handle material on the knife or if I had to use that handle material I would construct a different handle set up such as a frame, then put a butt end on the frame so I could swoop that bottom back using the frame's butt to do the swooping since the handle material would not allow the curve it needed to look right.
Or, take out the mid-swell on the bottom so that line contiuned correct which is the more simple fix but not always what you might be looking for.
That's my opinion.