I did my own panel (and the entire rest of the boat) from scratch this spring and was generally thrilled with the results. But I don't think cost is the right reason to do it. Doing the work is just too time consuming to skimp on the components and when you add things up the expensive panels you see in stores aren't bad at all (annoyingly, this seems to be true for most marine things).
I made my own panel because my space was too small, I wanted 8 switches, a lighter outlet, a gauge, and indicator LED's for everything in a small space. I had to make my own to do it. I bought all Blue-Sea stuff, including a $60 fuse/distribution block to go behind the panel.
That said I'll try to make another post tonight with some tips/parts. Blue-sea re-sells carling toggle switches and generally the electrical components can be had for cheaper if you want to look. Forget radio
shack - think Digi-Key and McMaster.