I was thinking about buying a Ford explorer

Is it really cheap?

More trouble than its worth unless its super cheap. The first body style is better than the rest except for the latest model (maybe) as I have not heard many reliability issues there atleast not like the other years. The others have transmission build problems (no Fix) and intake gasket leak issues and running hot problems leading to head gasket failures. The first body style with a manual trans have much better reliability and those in automatic trans were much better than the later body styles (except the latest body style). There is after-market parts for engine to help out with those issues but need it in Manual trans to be reliable.

Think about how many miles you drive each year. If you only drive a couple of thousand miles a year and the Explorer is in good shape it might last you for several years. Then again if you drive a lot it might only last a few months.