Diesel. There are 14 Regular gas price reports in the past 5 days in San Luis Obispo, CA. The average Regular gas price in San Luis Obispo, CA is $3.05, which is $0.29 higher than U.S. national average Regular gas price $2.76.The lowest Regular gas price is $2.93 of University Gas located at 1756 Monterey St, San Luis Obispo, CA 93401.The highest Regular gas price is $3.3 of 76 - Circle K Express located at 2015 Broad St, San Luis Obispo, CA 93401. days ago. $3.30update. There are 14 Regular gas price reports in the past 5 days in San Luis Obispo, CA. The average Regular gas price in San Luis Obispo, CA is $3.05, which is $0.29 higher than U.S. national average Regular gas price $2.76.