If you live in California, and trips to cave country are likely to be limited, you can do what I did. I looked at what the skills were that you need to cave dive, and how many of them I could actually learn in open water, and then I took classes in open water to learn those skills. Precise buoyancy control, non-silting propulsion, strong situational awareness, line running and following, and the use of double tanks are all things you can learn in open water. UTD Essentials or GUE Fundamentals are good places to start (even if you don't intend to do your cave training with those agencies) and both classes are available in the Bay/Monterey area.