help decide on 94 rodeo purchase

I'm looking at a 94 rodeo with 130,000 miles. It is 4 cyl. 5speed clean interior some scratches in the paint and the rear door won't open. When you put the key in the button it won't turn very far either way and nothing opens. We hate to twist to hard and break the only key off in the button. What is it worth and can the rear door button be fixed?