I live in the Bay Area and have both boarded and kept horses for over twenty years, and it should be doable on your budget if you are flexible. We currently live in Lafayette and board in the Briones/Martinez area, and I also own a horse property in the Oakland hills that we are currently renting out. We moved to Lafayette for the schools, but may move back to Oakland at some point since I actually prefer it there. I have commuted for years to San Francisco and the Bart ride from Lafayette or Walnut creek is about 30-35 minutes, and total commute time to downtown San Francisco is about an hour from our place. We are actually zoned for horses where we live now, but it’s fairly hilly on our lot, although several of my neighbors have horses and arenas. Lafayette/Orinda are expensive to buy because of better schools, but the adjacent communities of Briones/Martinez and Concord/Clayton are still places where you can find a small horse property for under a million if you search, and board can range from $400-750 depending on amenities. Castro Valley is also worth checking out. Apartment rentals in Lafayette or Walnut Creek are much cheaper than San Francisco. My horses are 20 minutes from our house, and I don’t mind the Bart ride. All are quite safe neighborhoods.
We had our Oakland hills property on the market last year for under a million (not for sale now), and it had an all-weather 70x135 sand/rubber arena, 2500 square foot renovated Spanish style house, 3 stall barn on a flat acre, and trail access. Not quite as safe as Lafayette, but we didn’t have problems beyond the occasional car break-in (very different than the inner city parts of Oakland). I have also lived and boarded in Palo Alto/Portola Valley, and it’s also very nice, but prices are very high there now, although occasionally you can get boarding deals in private backyard barns. Woodside horse park is great and I go over there regularly for events/shows.
For boarding options in East Bay Hossmoor is on the pricier end at $575-750, but has lovely pasture and big turnouts combined with very nice arenas/trails. I board at a place in Briones that is usually full but is about $435 for a matted stall with small run, including daily turnout into larger dirt paddocks, and a full size indoor and trail access. They feed generous quantities of grass or alfalfa hay twice daily and the horses are all pretty happy there. Free trailer parking and nice owners, and they even let our Pony Club meet there for free. For retirees and youngsters, I like Lone Tree in Waterford, which has irrigated pasture on 100 acres, divided by age/gender. I pay $255 for pasture board for my yearling there with safe fencing and a huge area of irrigated pasture with other yearlings, and they have excellent retiree care. They also have stall board and and indoor, as well as a cross country course, and regularly host clinics/hunter paces.
Advantages to living here: Good job opportunities, great food/cultural activities, liberal climate (advantage for us at least). Usually fabulous weather, active eventing/dressage and h/j scene, and terrific open space trail opportunities, especially if you have a trailer. Obviously housing is more expensive, but I’m often surprised that board is actually cheaper than many other areas like the East Coast, Chicago, or even the Seattle area. As a transplant to California I’ve found people are pretty friendly. I event at Prelim and have two daughters who do Pony Club, but I also know a lot of people throughout the local horse community and it’s not hard to find trail riding buddies if that’s your thing. Education is the weakest area, but hey, you don’t have kids so you don’t have to worry about that.