here indiana you can find single piece mohogn blanks(16 wide, by 20 long) for under 20 bucks.
and then a birch plywood piece at 1 inch think is 4 bucks, so you figure you are saving 4 bucks on raw wood(maybe more or less)
not including the cost of grain filler or filler in general.
i sold a big peice of mohogany online once(honduran, sp?) for 100 bucks but i only paid like 20 straight from the lumber yard.
the "tonewood, every wood has a tone" is true, but also take into acount the bracing, bridge thickness and size, and the pegs(unless is a mounted peice over a bridge)
there are so many determining factors in "tone" thru wood that it cannot be honestly said which "sounds" better unless you make two identical guitars*(down to the cut of the grain) but change one thing. i.e. scale length, top wood, bridge type, whatever.
its a long winded argument.
overall its the idea of plywood being less resonate.