In the immortal words of Hank Hill, Brooksie's sells "propane and propane accessories." Located on Arizona Avenue, they are convenient to most places in Chandler. They have great service and refilling your tank is a lot more affordable than switching out a tank at the grocery store.
They're not open very late, so check your propane tank before starting the grill. They also offer a nice selection of decorative items imported from Mexico.