California's Prop. 37 could provide $25 billion for homebuyer down payments. Learn how the middle-class housing measure works and its key caveats. That down payment amount is based on the statewide median $900,000 price tag for a house, according to recent data from the California Assn. In Los Angeles County, the median price for a single-family home is $935,000. In Orange County, it’s $1.5 million.