Sometimes I buy sandbox sand at Home Depot, but it is expensive if you need a lot. Ds has an 8 foot by 8 foot sand box that is 24 inches deep. . . so we couldn't do Home Depot. We called a landscaping company and talked to the guy about their cleanest, chemical-free sand ( also hear it is supposed to be big enough to not make dust that kids breathe) and they sold us "river sand." It was $70 for a very big pile that a dump truck had to bring! I wouldn't recommend actually getting sand from the beach. In my community the beaches close often for fecal contamination and other wonderful things . Yuuuuck. I hope your beaches are cleaner!
Those of you who took it from beaches. . . are the beaches clean where you live? In California the coastal communities dump partially treated sewage in to the water. People get rashes and such from water and a "poop scoop" (fecal contamination score) gets published in the paper. We do play at the beach, but then we come home and scrub ourselves clean!