I'm wondering what would happen if I put in the washer a dry clean only item.
It's a down comforter. It's white and it's getting dirty.
I called the dry cleaning to see how much it would cost and they told me $45.99 plus tax, WOW, I might as well just buy a new one.

Just wondering if you've ever washed something in the washer that said dry clean only, and what happened to it.

You definitely cannot wash down. I have washed plenty in the washer that said dry clean only but they were clothes that I knew would make it, but not down. Here in Canada a good down comforter, queen size is $l50. So to keep it looking and feeling good if I could dry clean it for 50 bucks I would do it.