We get a lot of calls about where to get airfills, where to rent gear for local diving, and where to buy gear. Depth Perceptions Dive Shop is located in San luis Obispo. This is the shop I have used for years and is the closest to Morro Bay. Depth Perceptions is located in the Bear Valley shopping center on Los Osos Valley Road. 
The selection of dive gear in this shop will blow your mind.  They have the largest and newest selection in San Luis Obispo County offered at reasonable rates.  You will Find brands like Oceanic, Atlan, JBL, just to name a few.  Probably the coolest thing is the owner, Chuck. Trouble with malfunctioning equipment or need annual maintenance? He will repair your gear on the spot if he can, and get you back in the water.  

As far as Spear Fishing Equipment Depth Perceptions of San luis Obispo Carries JBL, AB Biller, just to name a few.  Along with Stingers, Bands, Pole Spears, Spear Tips, Shock Cord, Float Lines, and Floats.  You can also have your Spear shaft Resized and threaded. 

Depth Perceptions
12322 Los Osos Valley Rd
San Luis Obispo, CA 93405
(805) 595-3631