Hello! I am glad to be a part of the Jeep Patriot community!

I agree with @Carbuff. The seller's story seems suspicious to me. CVTs are notorious weak points in the Patriot -- not because they are mechanically flawed, but because the maintenance schedule in the owners manual is tragically insufficient. Many Patriot transmissions (including my 2008) failed before the first service interval. Transmission fluid and both filters should be changed at least every 50,000 miles.

The seller may have gone the fool's route and installed a junkyard tranny, only to find out why the vehicle was in the junkyard in the first place. Now he's trying to sell his problem. Make the seller go the distance. Even so, as when purchasing any used vehicle -- especially a private sale -- have your own mechanic check it over for you. You describe yourself as a caveman, so be extra sure before you end up having to buy another tranny.

If the tranny is good, Patriots are otherwise pretty sturdy rides. Engines are very durable. My aforementioned 2008 Patriot was sold to a friend and it's now over 300,000 miles. My 2014 is at 190,000.