In 2021 we bought the building for $1.5M using private lenders, pushed the occupancy from 50% to 80% occupancy and it appraised for $3.125M, allowing us to pay back the private mortgage.Right now, we are in the predevelopment process of design and piecing together the capital stack for the redevelopment deal, which will be made up of historic tax credit equity, RestoreNY Grant, DRI Grant, etc.

Firstly, well done for persevering and trying every avenue you thought would get you the data you needed.Most would have caved earlier and handed out there hard earned cash for old, saturated leads/records from the same prominent platforms which dump them pretty much when they receive them from either 1).the same large brokers AFTER the county has listed them on the county website or, 2). from the counties themselves directly AFTER the county has listed them on there own website, or, 3). from data scrapers on Upwork/Fiverr who scrape the data from those same platforms AFTER the counties/brokers sell those platforms the data being scraped by the freelancers.Anyway, rant aside you seem to of made the same mistake i made when I first started branching out away from providing leads to my original couple of clients i got from Upwork who wanted me to scrape data from court records in FL for pre FC leads.Simply, I didn't know where to look for the information I needed in states outside of FL.FL only allows the judicial route to foreclosure so I only needed to know/find/scrape the data from Lis Pendens documents for counties they requested.

They have to collect the data, confirm the data, then publish the data for the public.

You may feel like a 6-7% rate is "high" but it is historically a pretty average rate.

And if your selling NON mls props its hard to run data..

Looking for guidance on options. new builds aren't hard to finance and I would argue they are preferred to existing fix and flip loans, especially if you have experience. banks look at your experience, your builder's experience, loan structure, permits, etc you need to get an experienced builder familiar with advanced underwriting and negotiations with local, regional, and national lenders. in columbus we do ground up construction for clients at a 20% discount so they can BRRRR out of the new build with equity and we have pages and pages of data on what we build and why and it's all supported by market statistics. 

+1  Real Estate Investing Data and How-to Guides - This here shows that you can filter to Multi family but I don't see it as an option as well.

What percentage of sellers are still contributing in some way, do we have data or knowledge of this?

Aside from the George Foreman Grill (yeah, those things are awesome right) celebritism for sales is historically a rule of thumb to gauge hokum not quality.Who knows, maybe Pace is "different", we will see.  

But usually for a tenant occupied it's like $90-120 per monthI've noticed a lot of multi-family buildings are pre-WWII housing inventory - are there restrictions or issues common with that (historic districts, crazy high utility costs, etc)?