It's oversaturated with crappy wholesalers who don't know ARV and can't estimate repairs costs. 

The estimated cost to finish the basement is around $25,000, with an additional $24,000 needed to complete the rest of the property.

Without a contract in place, and with no prices being quoted, or estimates made beforehand, we have what’s essentially an after the fact negotiation.  

Zillow estimated it 215k.  

I have gotten some estimates and that looks like about $30k total if I just use local contractors, If I do some of the work myself and do it as cheap as possible, I might be able to do it for $20k. 

You can use this tool to estimate future property taxes: https://treas-secure.state.mi.us/ptestimator/ptestimator.asp

I estimate the house could rent for $2.8K–$3K, while the warehouse might rent for (one unit) $2K–$4K, depending on how much work it needs to suit different tenants.

With an estimate in for the roof ($10,000 approximately).

You estimate vacancy at 8% which is conservative.

So, this is why your lawyer may have estimated high.