This one is listed for $10k locally - Las Vegas. Going prices for Expy's in Vegas are higher than most other areas. The engine is "new" 3 yr, unlimited mileage warranty. I've been taking my other cars there for service.
This shop has a repair history on the '07 going back to 75k miles. The previous engine had plugs replaced @ 132k miles - *By the dealership. They broke off the plug tip and left it in the cylinder....100 miles down the road, the valves tried to eat the tip, unsuccessfully. The shop has had it sitting for 2 years, and just replaced the engine, mid-December '18. The shop is offering 1 year/12k miles on the engine, w/ 6months on the rest of the drivetrain. I'm expecting that should be enough to discover any 'bugs' not immediately noticeable.
Screw that, that's '09 Navigator money... and no plugs issues there, only '07 and early '08
If things really are so bad in Vegas, Los Angeles is 4 hours away
But check cargurus listings and craigslist, you might be surprised.
And avoid buying from repair shops, that's probably a mechanic's lien (think "foreclosed for unpaid services"), so the former owners were utter flakes