Even as foreclosures fell to more normal levels, home sales in Southern California slipped to a four-year low in August as would-be buyers faced inventory and affordability challenges, according to separate reports released Thursday.

The median sale price climbed to a post-recession high of $420,000, according to Irvine real estate data firm CoreLogic DataQuick. That represents a 9 percent jump from August last year and nearly 2 percent rise from July.

The rise in pricing and lack of inventory pushed sales down dramatically in Los Angeles County, with 6,508 new and resale houses and condos sold, a decline of 19 percent from a year ago.

“Prices are high enough to be a hurdle for a lot of potential buyers, even though mortgage rates have fallen in recent months,” said Andrew LePage, an analyst with CoreLogic DataQuick, in a statement. “Some still struggle to qualify for a loan or to mend their household finances in the wake of the Great Recession. Others are simply waiting for price appreciation to give them enough equity in their homes to make a move up.”

A total of 18,796 homes sold in the six-country region, a 7.7 percent drop from July and 18.5 percent decline from last year. The median price in the region last month was $420,000, the highest for any month since December 2007, when it was $425,000, but still below the $505,000 peak earlier in 2007.

According to another report released Thursday, home foreclosures in the region fell in August, continuing a trend to a more normal market.

There were 7,163 foreclosures, down more than 16 percent from the same month last year, according to RealtyTrac, an Irvine real estate data firm. On a month-to-month basis, the rate dropped about 9 percent since July.

Housing experts noted another shift in the market, as institutional distressed-asset buyers, which have made a business of renting single family homes, have slowed acquisitions.

“Distressed property inventory in Southern California continues to decline as equity sellers continue to dominate the marketplace,” said Chris Pollinger, senior vice president of sales for First Team Real Estate, covering the Southern California market, in a statement.

In Los Angeles County, one out of every 2,726 homes was in foreclosure during August, down more than 25 percent from last year.

In the greater Valley, Palmdale and Lancaster again topped the list, each with foreclosures in one out of every 486 homes. Among communities with few foreclosures were Sherman Oaks, with one in every 3,969 homes; Studio City, with one in every 1,917; and Burbank, with one in every 1,707.