Lastly, I must add that in order to replace a lost key you will need to purchase a "cradle" that is sold separately.My own personal preference is that I do not recommend these locks for large complexes with multiple units.

I am currently in the process of getting a 6 unit apartment complex in Ohio and starting to try to get some quotes from several different insurance companies.I have a range from $5K - $7.5K....

Good point, but that's quite a complex way to look at it. 

I knew that larger apartment complexes were evaluated differently, but I didn't know that it would also be the case for, say, a simple duplex among single family homes.

This property is a penthouse on an apartment complex.

Actually, math more complex than the multiplication tables is pretty mysterious to me but just apply math.Dig in, research and work with people you trust.

Another one is I have a complex that is full with a 10-person waiting list.  

Is there even such a sweet spot?  

Hence, one reason why I'm interested in larger apartment complex deals (e.g., use the economies of scale to pay a property mgmt firm).

Drive around the area and copy down the addresses of other apartment complexes.