Property taxes are based on a percentage of the purchase price. In the San Francisco Bay Area, for example, the exact rate varies by county but is generally around 1.1% to 1.2% of the home's value. As a rule of thumb, you can figure on 1.2% for property taxes. The monthly expense would be figured as 1.2%/12=0.1% or 1/1000 of the purchase price, so, if you buy a $200,000 property, your taxes are $200/mo; a $314,000 property has monthly taxes of $314.
Propery taxes are due, in California, on November 1 (late as of December 10) and February 1 (late as of April 10). If the lender requires that you pay taxes through an impound account, the lender will collect different amounts up front, depending on the month in which you close escrow.