A renovated home for sale in Point Loma. Photo by Chris Jennewein It got a little easier to purchase a home in San Diego this summer, according to a third quarter survey undertaken by the California Association of Realtors, the trade group of residential real estate brokers and agents. But long-term affordability is slipping, in large part due to the recent dramatic run-up in housing prices. Here in Southern California, affordability improved from the previous quarter in San Diego, as well as Los Angeles, Orange and Ventura counties. In San Diego, 23{3e92bdb61ecc35f2999ee2a63f1e687c788772421b16b0136989bbb6b4e89b73} of would-be buyers could afford an average-priced home, an improvement of 1 percentage point from the previous quarter. But…