Inexpensive water softener salt brands include Morton, Diamond Crystal and Natural Salt. Depending on the form of the salt, such as pellets, cubes or crystals, the price for a 40-pound bag of Morton or Diamond Cystal water softener can range between $5.50 and $8.00, as noted by Lowe's.
Water softener salt in crystal form is cheapest, while pellet form is more expensive. The product is also available as solar, rock and evaporated salt. Solar salt, for instance, is formed from seawater when it evaporates in the sun.
Morton is a popular brand of water softener salt is Morton, according to BestWaterSoftenerReviewGuide.com. The company's products include System Saver II in pellet form and solar salt in crystal form.