ryan podesta already has the north of the peninsula with his 31st outfitters. If you could find some place thats accesible from oakland/san francisco/east bay within a 20 minute drive, that would be great.The only problem is that you run into many other problems such as security and really high overhead costs because of rent and such.
if you google paintball stores. you can see that there is a huge void of stores/fields in the yellow circle
just to illustrate
if you can get a store somewhere in the yellow circle, id probably be a customer at some point. the closer to the major city(san francisco/oakland) the more inclined i would be to go to your store since i wouldnt have to go completely out of my way as i would have to for the other stores.