I wanted to make a very basic cabinet for my bathroom. It basically required two long planks, yet the price of these two planks was more than buying a ready made cabinet from ikea.
One thing to keep in mind is that wood is more expensive the larger it is. Learning to assemble large panels from smaller scrap -- either decoratively with rails holding smaller panels or by just gluing everything together into one big flat panel -- can let you trade time for money in your projects.
Smaller pieces will typically cost less at the lumber yard, and it also makes it easier to work with salvaged wood -- you no longer need to find big pieces to salvage, you can salvage a lot of little pieces and build them up.
Also note that salvage isn't just dumpster diving -- at auctions and sales you can find large things people made for particular purposes that no one wants, and break them down for raw materials. I've picked up a couple hundred dollars of dimensional lumber for a $5 bid before because it was in the form of a 9 foot tall viewing platform for refereeing volleyball games.
That should clue you in as to how cheap the panels ikea uses. If you want to be part of the throw away culture buy ikea. If you want it to be usable for the next 300 years spend the money on real wood.
