2009 Outback Rebuild or Replace?

Head gasket leaking internally. No warning, so cylinders are bent. Dealer is
quoting $3K+ for the head gasket replacement and $1K for the cylinders (if
they can be machined). I know it'll end up being a few more K on top of that,
in the end.

What should we do? Rebuild? Buy used engine?

2009 Subaru Outback, 4cyl 2.5i Special Edition- non turbo, almost 57K
miles.

Subaru of America/Dealership has no intention of taking any responsibility
for the faulty head gasket that caused the mess. They say the car
overheated which caused a whole host of things to fail. Problem is, we had
no warning. Took it for regular, non dealership, maintenance (They don't like
that). One day, no A/C, then "is that sound from the car?", then check engine
lights, then HOT.