Crystal malts can be found at homebrew store. If you can't find it locally, check out websites such as www.northernbrewer.com, www.midwestsupplies, www.brewmasterswarehouse.com, and etc. The 30L, 60L, etc is called the degrees of lovibond. It describes the color of the crystal malts. The higher the number, the darker the malt. You can find crystal malts ranging from 10L to 150L. Each crystal malt will also have a different flavor profile. Reading the following links might be helpful.