One of the freezes here my driver door was stuck so I went to get into the rear driver side door and the handle made a thunk and I could hear the doohicky pin dealio fall inside the door. I hadn't really tried to get the door open from the outside since then and I hadn't taken the door card off to fish the piece out.
I'm betting someone's had this issue but I can't find it by searching, I'm guessing just get an assortment of roll pins and find one that fits to fix it up.
Roll pins typically are a press-fit and do not fall out. I'd be surprised if that is what fell out. I'd have to take the inner door panel off and see what needs replaced.
I've had door handles replaced for relatively cheap at body shops. I always ask for the cheapest cost when doing something like a painted door handle and I have never been able to tell the difference. I think the last time I did this is costed less than $100 and zero time and effort.
I'd like to offer a little advice, speaking from my unlucky experience with my outback....don't let anybody set the child door lock safety thing on that door...otherwise you won't be able to open it from inside nor outside and it'll be a real pain to get the inside panel off and get the door handle fixed.