Don't know what type of pencil you are thinking of using/making but for the pentel mechanisms this place has good prices on the .9 and .7 mm pentels and free shipping if your order is over $50.
I made a pencil a while back using a Sierra pen kit and loved how it turned out. It's my favorite pencil and I use it everyday. I would love to make another one using .9mm because I use red for corrections for my job and the .9mm red lead looks and works better than the .7mm does.
Pentel. If you haven't made a Pentel, it's a great pencil to make. A bit tricky the first couple of times but once you get the hang of it, it's a snap.
**Edit*** I forgot to mention that you have to specifically find the .9mm b/c the Pentel comes in .5, .7, and .9
I got my .9 at Staples for a few dollars each. Finding .9 refills might be a bit trickier.