Making your own stock is easy, it just takes lots of time.
Go to a lumber yard, get a solid, dry piece of hard wood, then just drill or mill out an area for the action and cut off all the wood that doesn't look like it's suposed to be there.
Seriously though, it's not hard if you think your way through it.
I glued 4 pieces of plywood together, squared it up, and after hours of sitting there figuring out the best way to make cuts and a little time cutting and filing I ended up with an unfinished stock.
I never finished it though and just scrapped it. It was a practice run from the start and I don't have time to finish it.
What I did accomplish is the knowledge that I can make one (and I plan on making at least one nice one some time) if I wanted.
The most difficult part is measuring out where to inlett the stock for the action.