I found a 1996 Jeep Grand Cherokee Limited that is fully loaded, looks new, runs great, but has 320,000 miles on it! Should I buy it? How long do the GC's usually last?

And I thought my 95 GC had high miles (107,000). I will assume your GC has the Inline 6 engine. That engine is built for the long run. The longest I've heard of a GC I6 lasting is 260,000 miles. I would beware of problems at this point. But it should be cheap, and if the interior is in good shape, I would say go right ahead and buy it. And with the money you save on it, you can always get an enigne swap from at least a 98 GC for about $5000.

Go for it, as long as its less than about $800. More than that and it may not be worth it.