Go diving in the kelp just off shore from the cliffs...you are from the Dakotas so the 60 degree water temp should feel like bath water.
As for shops, I wasn't in the hobby when I went to college there, so I'm sorry I can't help you out.
crystal cove in Murrieta about a hour from down town san diego 15 north exit Murrieta hot springs go left make first right on madison and it is across the street from best buy. his place his huge!! and has super hard to find fish.
two other smaller shops in the area, gills super nice guy, and far west smaller shop by the mall but he deals and has good prices.