car-part.com for used trans pricing and availability. 2013-2017 Outback CVTs are interchangeable even though that database says they are not. I’ve never checked into 2011 comparability but you might have more options than it lists.
He’s wise for installing new - saves him and you the headache of used parts issues. And Any aftermarket rebuilt AT for Subarus should be avoided.
The glaring omission here is why was he looking and how did he check?
”presumably” - does this mean you just got the car? If so, there’s a good chance you just bought someone else’s problem after they got the same quote and sold it to you. I see this happen all the time.
Enough of that Sherlock Holmes talk - back to the omissions:
If he checked via the dipstick I wouldn’t consider that a reliable diagnosis. Drain the fluid and check.
If it was drained, why was it drained?
Or did you have symptoms that promoted looking for issues?
Transmissions can have debris in them - the magnetic rings always have built up debris on them over time in the pans. So you’ll need to describe this “shavings”.
But yes - “shavings”, in the way I’d use that word is absolutely catastrophic for an AT. That said - I could envision plenty of scenarios where I’d fill it with new fluid and see what happens. As annoying as those are to fill.
2017 CVTs work in 2013s, not sure if they go back to 2011 but that might expand your used options if you need that route