Where is a good place to buy used auto parts?

My sunroof is malfunctioning and I am trying to fix it myself. The local dealerships charge ridiculous prices for parts.

I know there are auto yards where you can scavenge parts yourself but what are the odds of finding the right sunroof motor?

Is there any kind of online warehouse or info clearinghouse you can recommend?

I expect answers about used parts in general, but if anyone has a line on a Subaru sunroof motor 65450SA000 or 65450SA001…