3.5 L V6 life expectancy?

I realize there is no standard life expectancy for any engine but should I think a 2007 MKZ with 191,600 miles would be a decent purchase for under $5000??

That depends a lot on the maintenance record for the MKZ. Does the seller have any maintenance records for the car? What kind of shape is the rest of the car in? Generally, if someone doesn't take care of the interior or exterior of their car, they likely don't take great care of the engine either.

-Rod