We are clearly talking about a good grade of wood here, not something equivalent to a Best rifle. Call it Marlin grade. Good wood like walnut is very cheap, actually cheaper than Maple in many cases. One has to distinguish between black walnut lumber and various stock species that are harvested just for the gun trade. The "walnut" that ends up on most factory rifles is just a good grade of black walnut, no different in any way than wood used in furniture, veneer, etc... Architectural interest in white woods has driven maple through the roof. 10 years ago I could get maple for $2, cherry for $4-6, and Walnut for $6-8. Now maple is often $10. All prices are for a board foot which is a piece containing 144 cubic inches. If you buy from wholesale sources your proces will run from 0-$2/board foot, for any of the above. The zero being form tree services and other free occasionally free sources. In most cases you will need a few years to dry it. There isn't any difference in the dryig rate for woods by geographic location, except as that affects species.
The basic issue is whether the wood is going to be checkered since it takes a compact wood to take checkering, you could still use cherry, brich, maple, or walnut. Beyond that it's structural. You could probably get away with poplar if you were willing to glass it, same with most lighter species. Glassing is pretty easy, however, getting every nook well bonded in requires a bit more skill than you might imagine. I have seen softwoods used for alpine stocks and stuff like biathalon stocks. It's a tricky business since you have to know how to take the loads off into the light material while maintaining overall strength.