i was wondering how much do you calculate for your insurance in Essex County NJ?

i have one company saying i need $825,000 (thats $147 per sf) coverage for a building of 5,610  square feet, and one company said i ony need $675,000 (thats $120 per sf), it is a building with bricks just for the first like 4 feet then its siding.

please let me know    thank you