Where to save money for a future all cash purchase
My wife and I are interested in purchasing rental properties on a buy-and-hold basis when we settle down in Northern California in about 9-10 years. She is currently a medical student and obligated to serve 8 years in the Air Force starting next year. Our goal is to settle between San Francisco and Sacramento and build a real estate portfolio while she practices as an attending OB/GYN.
Starting in mid 2015, we should be able to set aside $10,000 a year to save for real estate. We should be able to add $5,000 a year to that amount, so $15,000 in year 2, $20,000 in year 3, etc. While I'm aware of the power of leveraging, part of keeping a happy wife means keeping any business activities paid for in cash.
For a 10 year timeline, should I just put the money in CD's, savings accounts, etc? Or should I look at something like a low tax, low fee S&P 500 index fund? Volatility is a concern, I don't want my investment to drop in half at the same time the real estate market takes a dive like in 2008.