We built a super easy and cheap industrial bookshelf last weekend and it only took about 1 hour and costs around 50 bucks!! I will include links to all materials that we used for this project.
First we started by going to home depot to pick up the materials. The great thing about this project is that itis customizable to exactly what you want or need for your specific space. To start we decided that we wanted 4 shelves to store our books on, so we purchased 4 boards that are 10 inch by 6 feet by .75 inches. These are called common boards, follow this link to find them http://www.homedepot.com/p/1-in-x-10-in-x-6-ft-Premium-Kiln-Dried-Square-Edge-Whitewood-Common-Board-914894/100022066?keyword=1+inch+by+10+inch+by+6+feet.
After we bought 4 of those, bringing our total to 32 bucks, we bought 8 cinder blocks at around 1.50 each. After taxes our total was around 40 dollars, and then we bought 2 cans of satin vintage teal spray paint http://www.homedepot.com/p/Rust-Oleum-Painter-s-Touch-2X-12-oz-Satin-Vintage-Teal-General-Purpose-Spray-Paint-316292/300531644. Then we spray painted the cinder blocks the satin teal and I think they turned out really nice.
Then we bought 4 cans of white spray paint, and we should have just bought a small can of white paint and it could have been much cheaper http://www.homedepot.com/p/Rust-Oleum-Painter-s-Touch-8-oz-White-Flat-General-Purpose-Paint-1990730/100168895.
Finally just wait for everything to dry and start stacking, and then you have a really cheap and industrial/modern bookshelf.