One Bedroom Apartments For Rent In San Marcos California . Find san marcos properties for rent at the best price. Find 1 bedroom apartments for rent in san marcos, california by comparing ratings and reviews. Room in 1 bed apt at California State University San Marcos, 333 S Twin Oaks Valley Road, San from rentberry.com Listings, photos, tours, availability and more. Choose from 18 one bedroom apartments in san marcos, ready for you to rent! As of june 2022, the average apartment rent in san marcos, ca is $2,559 for a studio, $1,984 for one bedroom, $2,227 for two bedrooms, and $3,772 for three bedrooms.