Look at Wanna Get Away fares on WN OAK-BUR. Or LAX.
Book in advance, I think 21 days, and the one way fare s/b between $59 and $89. Nice thing about WN is you can book in advance knowing that if your plans change they make it very easy to cancel and rebook. No refunds, but full credit to "Travel Funds" which you can apply to any future travel within a year of your BOOKING date (not departure date). The system is keyed to the cancelled flight's Confirmation Number, so keep track of those or it can be hard to find your funds.
Btw, I flew between Northern and Southern California twice a week for 5 years straight and had less than 6 IRROPS.