Barron’s grocery store sells Julian apples in season. They are small and a tad sour, but very good. I buy them every year. They hit the sweet spot, less sour than granny smith but more than all the other varieties.
Why are you trying to build your own home? When I’ve browsed deep-east county listings, it seems that supply is very high compared to the rest of San Diego, and you should be able to find exactly what you are looking for without the hassle of building yourself. And if the location is really good and OK for development, someone would have already built something on the lot.