Miami Beach home owner insurance

[Idan L.]

Hey guys 

I am prospective new home owner who's about to sign a purchase agreement for single family home 1931 old house with reletviltly old tile roof last done about 30 years a go the house is elevated about 6.6ft 

recent quotes had gave me about 24k in insurance while old owner pays 8400 and some other friend of mine who just finished renovating his house pays around 12k

what am I missing here as this would be a deal breaker for me 

the house purchase price is 1mil