Hawaiian and Alaska Airlines have round-trip flights from Dallas (DFW) to Portland, Oregon (PDX) for $128-$149, NONSTOP. Flights October to February. Departures on Tuesday, Wednesday, and Saturday. Origin/Destination reversible.
Some small OTAs on Skyscanner have this for as low as $128; which is cheaper than the airline. If you plan on booking there, beware of any site that charges a fee to cancel a ticket within the 24-hour “free” period. Use unknown booking sites at your own risk.