basement finishing

Anyone here has a slate roof on their home or has any experience dealing with these? I'm currently looking at a home with slate roof shingles that requires some minor attention.
My father and I have discussed that if I purchase the home I should look into just stripping it and putting on a nice metal roof that looks like slate because the cost is too great with slate.
So is it too expensive to fix? Are the slate tiles worth anything to those looking to use slate on their homes?