If you have no source for referrals, you might want to Google the areas of interest, and find Realtor blogs and websites that interest you. Then, feel free to call or email the agents to find one with whom you feel most comfortable.
Any seasoned agent in North County would be familiar with the markets in Encinitas, San Marcos, Carmel Valley --and most likely Rancho Penasquitos.
As for the real estate crash in San Marcos: This area had an enormous amount of new construction (eg San Elijo Hills) that offered E-Z financing along with fairly stiff HOA and Mello Roos fees. This, coupled with San Marcos condo conversions that ultimately failed, led to a high number of foreclosures and short sales that have precipitated the steep decline in San Marcos real estate prices.
Today, some tremendous real estate bargains can be found not only in San Marcos, but in Carmel Valley, Encinitas, Carlsbad and Rancho Penasquitos. Count your lucky stars that you are a buyer in today's market, rather than three years ago!