For basic boxes, cruise the backside of the outlet mall. Sometimes you can even score bubble wrap from one of the electronics stores. Specialty boxes are sold at Miramar Self Storage (behind Copper Grill) 837-3951. I'd guess the other mini-storages sell them also. Home Depot has a good price on wrapping paper.
Or you can check craigslist or freecycle for someone getting rid of boxes from a recent move. Good luck!