Determining Amount of Insurance Coverage

[Neil W.]

Closing on a 4 unit soon.  Purchase price and appraised value is $210,000.

Received an insurance quote with replacement cost of $450,000 with premium of $3,200. Received another quote with replacement cost of $275,000 with a premium of $2,100.

I'm skeptical that true replacement cost is $450,000 and am considering insuring for much lower to decrease annual premiums. 

What percentage of replacement cost do you guys typically insure investment properties?  Is there an easy way to estimate replacement cost?

Thanks.