grab them on southwest and you can always rebook/cancel the flight with no penalties if something comes up. the funds though won't be refunded and you'd have a $259 credit on WN. you can also download and check their DING specials. I think they had some cheaper flights from PDX to the bay a few days ago (OAK I think)

in general though, flights to/from PDX seems higher than normal on all carriers. I guess when Portland gets it's two months of sun, everyone wants to go there