This is the best plastic store in North County San Diego.  Although primarily a radio control store, they have the best selection in the area of plasic from all the major manufacturers and a well stocked paint rack and supply of glues.  Beats the heck out of Hobby Lobby, Michaels and other "Craft stores" for the serious builder.  They also often have several people who know plastic behind the counter.  They do discount for IPMS membership but you have to ask.  Also very good at ordering special items.