@Dario Furman Detroit can be a difficult place to sometime find good insurance rates. There are many great areas but also many "war zone" areas. This can make insurance rates feel like they are all over the place with pricing. The reason the rates fluctuate so much is because each zip code will have their own rating factors and some zip codes may be completed declined by certain carriers. For SFH Foremost offers a great product that you can use for both the rehab phase and then convert the policy into a landlord policy. For multi-family homes can also look into Tower Hill, American Modern, Travelers and Safeco.
Was the quote your received from NREIG for a vacant rehab quote or a rental landlord quote? Vacant quotes are always going to be more expensive and I always recommend getting a quote for both so you have an idea of the what pricing will be once you rent it out. Hopefully the rehab is quick so you will only be paying for the ore expensive quote for a few months.