The owner's agent (not a realtor, just a friend, I think) believes that the property needs a new roof and he estimated $50k for a re-build, but I have no idea how experienced this guy is with such things.  

Another is to buy and rebuild a failing business from a don't wanna.

I have found that most carriers are in the range of 800-1300 annually if you are looking for full rebuild cost with a $2500 deductible. 

if you have a total loss, do you want to have enough money to rebuild the properties, or do you want enough money to get your investment out (market value) and live to fight another day?

Just get back to work and you can rebuild it all.

If there's anyway you can maybe rehab it up and maybe do some additions, you might be better off than rebuilding from the ground up due to the costs and time involved in that.  

I'm rebuilding part of the basement right now because of a mold problem which was mostly the tenant's negligence.  

What was the cost to rebuild when it burned down?

After talking to the realtor and a contractor it would be roughly 500k to purchase and rebuild, comps in the area show the house should sell for at least 700k new.

The cashflow on the small apartments I'm analyzing should be good enough to rebuild my DP funds for the next deal pretty quickly... or so I hope.