United Airlines and Alaska/Virgin America are putting flights between SFO and LAX on sale. Flights start at $79 after taxes, with dates found from through April.
With United, this fare is only for basic economy, costing between $19 and $38 more (depending on the flight) to get regular economy. Because of this, booking an Alaska/Virgin America flight is the better deal.
To find this deal, use Google Flights and search for flights between SFO and LAX.
Josh Trips 