Is $28,000 to repair roof with existing tiles a fair price?

I'm looking for information as this is new territory for me. We're buying a house in the LA area that was built in '87 and has a red tile roof. We need some roofing work done to replace the underlayment (likely original), and any wood issues they may find. When they put it all back together, I'm wondering if it's foolish to use the same tile and only replace the broken ones. There are only a handful of broken tiles now, but I know that more will break during removal and reinstall. Of course I'd like to save that $8500, but plan to own the house 'forever', and want to do the right thing in that regard. I'm looking for opinions.