I understand that Molinari Deli on Columbus Ave in SF sells the 6-in-1s. Since the 6-in-1s are a California tomato sold by Escalon, a California company, I would think that it they would be fairly widely available in your area. If not, they can be bought online from Escalon by going to escalon.net. Their shipping charges are reasonable so it may be cheaper to buy from them directly than from local merchants.
Another possibility is to call Italfoods (650-877-0724) in SF. They carry the 6-in-1s but unfortunately they don't sell to individuals. But they should be able to tell you where to find them locally.
Maybe one of out SF-area members or one of out tomato experts can offer some assistance.