For the hobbyist woodworker the cost of wood, relative to time and tools, is pretty cheap.
It's like someone who races a car as a hobby complaining about the cost of petrol. Yes, it's a chunk of change, but compared to everything else it's just not that significant...unless of course you're building library bookcases out of rosewood or something similarly extreme! But for most hobbyists I'd say ignore the price and buy generous quantities of the very best wood you can find, rather that than invest scores or even hundreds of hours in a project, and at the end be disappointed because you used cut price materials.
The other reason why I believe money spent on great wood is never wasted, is because we're all trying to distinguish our work from commercial alternatives. And one of the best ways of achieving that is with careful wood selection. I was looking at some oak furniture in Liberty's recently, and it was pretty impressive, solid timber with plenty of through-mortice joints and other evidence of quality construction. But the one thing that immediately let it down was lack of care in choosing and matching boards for the very best effect. But even the most skilful and passionate woodworker wouldn't be able to do much better if they've just got the bare minimum of wood for a cutting list.