Luan board would probably be pretty good as it should fracture kind of like a bone would. Where would one get some ballistic gel and how much would it cost?

You can get the balistic gel from differnt places, none of which I can remember. If you look in some of the gun Mags you may find a supplier. I will keep my eye out as I flip through the pages of my guns and ammo. I am sure if you did a search on google or even asked the question in the guns forum you would find out where to get it.