Potentially nice driver for $2500. 1989 mercury cougar - cars & trucks - by owner - vehicle automotive... (craigslist.org)
While I could definitely believe that it's rusty being that it's in Michigan, it could just very well be another example of a car that no one really wants or cares about. Most 1980s cars are relatively undesired because the collectors don't care much about them and poor folks who need basic transport can't really rely on their vintage electronics and sensors that are becoming harder and harder to source. Most of the folks you see driving these kinds of cars are mechanics who can fix them, relatives of the original owners who got them as a hand-me-down, and the occasional fan\owner who bought either new or close to new and is still enjoying\living with it. If you're on a limited income and need a reliable car to get to and from work, you get a Honda or Toyota or whatever has a warranty from the low-end of the dealership network. I still like these cars but the v6 was a little wimpy. Compared to "modern" cars they are downright tiny when you compare them side by side with another from +2015.
I liked the styling on these - a 180* turn-around from the '83 - '88 models I thought were pretty ugly. Let's compare, shall we. I'm going to use pics of more or less 'sporty' Cougars.... 1988: 1990 (I think) Only thing detracting these early models from being great cars were the stupid electric-powered (on tracks) shoulder harnesses. These first ones weren't initially designed for air bags, so they had to put a passive belt on them to make them legal. I think starting around '91 or '92 they had air bags..... EDIT: I was being overly optimistic. T-Bird and Cougar both got new dashes and driver/passenger air bags in the '94 model year.
I would have bought the blue '89 if it didn't look rusty. I've looked at enough of those up here to know when to not even bother contacting the seller. It would probably be okay for a few years for driving. The V6 is no powerhouse, but it's capable of surprising mileage and they run forever. The red car above is an 89/90 XR-7. Clone to the one in my pole barn.