Question about MUNI and Bart, traveling from Berkeley to San Francisco?

I am new to the Bay area, and was wondering about fare options for my commute to work. I live in Berkeley and travel to Stonestown galleria in SF. I take the Bart from downtown Berkeley to Daly City, then hop on a 28 bus, which costs $8.20 a day, 5 days a week. Is there a less expensive option, like a monthly p that would work for me?