Never rehome animals for free - too many people have bad intentions. You can contact Oregon Humane Society or The Portland Guinea Pig Rescue.
Put them on Craigslist for free
SW Washington humane society will likely take them. There may be a fee but it's better than giving them away, as there are lots of people looking for food for snakes, bait animals, etc
Dont put them on Craigslist unless you want them as snake food
I think Jenn has the best answer
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