I"m truly sorry for you. Some asshole blew the turbo on that car before and replaced it and immediately traded it in. We see this all the time and it sucks. I put up a thread about ethics when it comes to trading in cars, and unfortunately, there are a lot more out there that don't give a crap about anyone and they do that rather than fix the car.
Just noticed you said it was the OE turbo at 154K and most likely what the PO did was find a used turbo to put on so it looks like the OE. A LOT of that goes on. Again, sorry for you. Certainly can give you a bad taste regarding Subarus, but know one thing that when you have it right, you'll not beat these cars for bang for the buck.