About 2-3 years ago our 2013 Impala roasted an engine. A cam sequencer failed, it threw off the timing, the pistons ate the valves, and that's that. $2500 for a junkyard lower mileage (I use that term lightly) engine installed by my mechanic.
Same year, our 2012 Malibu that the kid was driving had a cam sequencer fail on the echo tech 4 cylinder. Same deal. Throws off the timing, pistons eat the valves, metal goes everywhere, and poof! I took the valve cover off, removed the spark plugs, rotated the engine over by hand and only about half of the rocker arms moved. Toast!
That was right around $4K with 1 year warranty used engine. Both cars are still being driven daily, so cheaper than car payments.