I see a lot of spice racks and other wooden organizers in the blogosphere built with pine 1x4 or 1x6 lumber. These are functional pieces and the lumber chosen works fine. What you may not know, is that most home improvement centers stock 1/2" hardwood stock now (rather than the 1x material that is 3/4" thick). For instance, half inch thick poplar is about as strong as 3/4" pine, takes paint better, and will give your project a more refined look. The 1x4's on the other hand have a rather bulky look, and take up more space (so, if space is dear--which is usually why the project is undertaken--look for thinner stock).
The last spice rack I built only cost about $8.00 in materials (the cans of spray primer and spray paint cost more than the wood), even though I used the slightly more expensive 1/2" poplar stocked at the local Home Depot. Also, instead of leaving the lumber square, I added decorative ends to match the corbels already in the kitchen. Always look for ways to make what you build fit the style of the home. I just used a jig saw to add these simple details and then sanded the jig saw cuts smooth.
Small pieces like this actually require no nails, screws, or other fasteners, just clamps and glue. Clamps may seem expensive, but can