1997 Chevy Corsica Exploding spark plugs

This friend is trying to sell me a car. The car seems ok. However he told me that the only problem was that two spark plugs exploded a while back. is that I should be seriously worried about? I expect some minor repair cost. But is this something that is a big deal and cost me a lot. In one way he is trying to help me out and sell me a car for $300. But I also dont want to be stuck with a car that will cost me $700 to fix.