https://seattle.craigslist.org/see/rvs/5687026783.html
Not mine, but they pop up in the Seattle area. There is a Casita owners group on Facebook that has a few for sale too. Casitas are great, I love mine. Good luck in your search!
There's a classified section about two thirds of the way down. Knowledgeable and helpful group here. Casitas are great campers but suggest you check out some of the other brands just to see what's out there.