What are the cheapest areas of San Diego county?

I live in north San Diego County, Oceanside, but for the area you are questioning, I would recommend La Mesa, its a blast from the past..they have a downtown that has some old mixed with new. Great antiques, eateries, shops, library, close to medical centers and a large mall. Houses are reasonable, as are apts, and condos. Close access to all major freeways too. Good Luck