Some material components can be crafted or found - others have to be bought. A useful feat, when you can take it, is Eschew Material Components - level one of it covers spells from first to third level, level two from fourth to sixth, and level three, seventh through ninth. The only problem is that A: you have to burn the feat in order to use it, and B: you can only take the feats once you can cast third, sixth, and ninth level spells respectively.
