SAN DIEGO (CBS/AP) — Home prices in the San Francisco Bay Area approached four-year highs last month as buyers snapped up more expensive properties, according to a San Diego-based research firm.

DataQuick said Wednesday that the median price for new and existing houses and condominiums in the nine-county region reached $421,000 in July, up nearly 13 percent from the same period last year. It is the highest median price since August 2008.

Sales rose 23 percent from last year to nearly 8,500 homes.

DataQuick said homes costing at least a half-million dollars made up a bigger part of the Bay Area’s sales mix, lifting the median price. Foreclosed properties, which tend to a sell at steep discount, were a smaller part of the sales mix.

Median sale prices in San Francisco, Alameda, Contra Costa, Santa Clara, Solano, Marin, Napa, San Mateo and Sonoma counties all increased in the past year with Napa County seeing the biggest price increase at a 32.6 percent jump.

Median prices in that county were at $281,000 in July 2011 and reached $372,500 this July, according to DataQuick.

The highest home prices in the region this summer are in San Francisco with $714,000 listed as the median cost, while the lowest can be found in Solano County at $188,000.

Statewide, home prices also approached four-year highs last month. DataQuick said the median price for new and existing houses and condominiums in California reached $281,000 in July, up nearly 12 percent from the same period last year.

It is the highest median price since September 2008 and the fifth straight month of annual gains.

Sales rose 14 percent from last year to nearly 40,000 homes.

DataQuick says properties foreclosed upon in the previous year accounted for 22 percent of existing-home sales, down from 35 percent a year earlier. www.cbslocal.com