I can help you with your question.
You can still (possibly) get a less expensive fair by going to the airport the day of travel and inquiring at the airline for standby tickets.
You can also sometimes purchase a "standby" ticket in advance directly through the airline (as strange as it sounds).
The best advice I can give you for standby is to only bring one carry on.
Checking bags, for obvious reasons, complicates things.
Based on the route you want to fly, I think your chances are pretty good of getting on a flight - never guaranteed - but those flights don't appear to be fully booked on a regular basis.
There is a great deal more detail at the following site for tips on successfully fying standby: How to Fly Standby
Please let me know if you have any questions!
There is also one more place I would suggest checking. Allegiant Air aggregates flights and they offer this route for <$300 and the tickets are almost always available for Friday to Monday (those are the only days for which they aggregate tickets for this route.
When I checked, 2/15 from OR was about the only day that didn't show availability (the reverse trip is available). So they may not be sold out, or you may be able to check back there frequently. They sell tickets online up to the day before the flight. You can also chat with one of their agents.
Here is the site.
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Have a great night!