That's the lowest price we could find for select routes by at least $35. Buy Now at DealBase Tips On the DealBase landing page, click "United Airlines" in the top line to see this sale. We found this price on flights departing from San Francisco, CA (SFO) with arrival in Ontario, CA (ONT) on January 13. Book this travel deal by January 2 for travel through May 20. All prices, dates, and booking details were valid at the time of publication.