First off i dont know anything about these cars and neither does the person selling them other than they were running when parked and had issues, and havent been crank or run in over a year with unknown issues on both... Prices should reflect that i think. Prices are firm aswell.
1991 BMW 318I
Possible blown head gasket?
http://charleston.craigslist.org/cto/5142139157.html
1987 BMW 325E
Unknown issues?
http://charleston.craigslist.org/cto/5142144683.html