Many of the major insurance carriers that I've called say they have never heard of such a policy.

The only thing I would add is most commercial insurance carriers will accept buildings 4 units and greater, so there couldbe other options out there that can compete with Foremost. 

Each carrier will evaluate the property and determine what the cost will be and that's why each carrier has a different premium for the property with generally 85-90% of the coverages being the same.If you feel the dwelling is low see if they have a guaranteed home replacement endorsement that can be added or 150-200% dwelling coverage to truly protect yourself in the event of a total loss.The market is going to be like this until 2025 most likely so the easiest thing to do is raise your deductible without sacrificing coverage.

There are more carriers operating now so rates have settled, even declined. 

I would speak to your insurance carrier to get more clarity.

I would get this out to quote with multiple Independent Agents (they represent multiple carriers) and if you can determine any agents that write a lot of apartments that would help also.The type of info you should gather that will help in the quoting process:1. current coverage. 

I'm surprised that your insurance carrier is still covering the property though with the roof being that old. 

I've used this insurance carrier for a while and I have a premium policy so it should all be fine.

If the agent blows me off for more than 24 hours, I get it delivered to the original seller by hand through a carrier.

They will have a network of carriers for you.