According to Suze Orman, housing prices aren't going anywhere, and interest rates aren't going anywhere. If you don't have 20% to put down, you should probably rent for at least another year. Your stocks might go down even more. Whatever money you have for a down payment, you should probably start moving it (or just adding to it) to a money market account or CDs.
When we bought our house (January 2006 -- ugh), we didn't anticipate that we would need to replace all of the carpeting due to my daughter's allergies and replace the entire HVAC system. We also decided to remodel one of the bathrooms and add a brick patio just because we couldn't get enough of watching our nest egg disappear ;-) We have put at least $100k into our house for repairs and upgrades. It is currently worth about $30k less than what we paid for it.
The stock market is pretty volatile right now, and for you to cash out and put that money into the real estate market, that can be quite risky. If you're not 100% sure that you are done having kids, you might regret the house you buy if you end up having more kids. Don't forget about the financial devastation that could happen if you have a fairly large earthquake too.
You've got plenty of time to put yourself on more solid ground financially. Ideally, you should have 20% to put down on a house AND have an 8 month emergency fund. Maybe you can find a nice house to rent and sign a two-year lease so that you know you won't have to move again for at least two years. And meanwhile, start socking away more money for your "forever house". Good luck to you!
ETA: $600 is an average middle class house in San Clemente. $400k is probably a decent-sized condo or townhouse.