Most managers are on just these sites and perhaps their direct websites, but the others are realistically the primary source. 

they need one of those and their license needs to be mentioned on the first page of their website.

And once I finish the due diligence, my work is done: it's completely passive.

I have kicked the tires with a few small investments in both long-term and vacation rentals offered on the website over the last few months. 

Assets identified in this study include:Appliances: Dishwashers, laundry machines and refrigeratorsElectrical and communication systems: Specialized equipmentCabinetry, Countertops and shelvingInterior Finishes: Laminate flooring, carpet, and decorative elements.Security and communication systems: computer connections, alarm systems and telephone connections60.8% of the total depreciable basis was classified as 39-year class life.

I am also looking for a HELOC to not have to pay out of pocket to finish this and just use the equity in the home.

Here's a https://www.irs.gov/businesses/cost-segregation-audit-technique-guide-chapter-4-principal-elements-of-a-quality-cost-segregation-study-and-report to the IRS website noting specific items that are included in the cost segregation study report.

I find market price with a combo of that website and looking at what other LL's are asking for on Facebook Marketplace.

There's no need to waste anyone's time to finish reading a script.

Section 8 rents for the entire country by locality are on the HUD website, HUDuser.org look for Fair Market Rent (FMR) there.