I'm not looking for anyone who sells to the secondary market (FNMA, Freddie etc...).Located in IL

Unfortunately, since these aren't institutionally originated notes, there is a small secondary market to sell these into. 

I was hoping to do a sellers carry for the down payment: So it would look like 75% mortgage, 10% down from me, and 15% from the owner (which would be a secondary loan).

@Jason PerryLet's clear the math first.

Vacancy, turnover, repairs and CAPEx need to be included in your math.

While saving to do your own. 2021 opens the secondary market for Stock that might be held making it more liquid for RE https://www.startengine.com/bl...

Math is real. 

. - Conventional loan with less than 20% down: Monthly PMI goes away after equity meets a specific threshold (somewhere around 78-80% LTV)- Conventional loan with 20% down or more: No PMIAs a buyer, I'd opt for conventional loan IF the down payments are close -- do the math.

The math part is simple, and significant when compounded over years. 

Your experience will probably be the single greatest factor for a higher or lower interest rate)Property Type (1-4 Unit properties are the most bread and butter for most HMLs, but I'd imagine some here would argue that point)FICO (Yes, even asset based, hard money lenders still take your credit into account and it can adjust your interest rate with most. 700+ is ideal, but of course there are HML's who will go down to 600, and those who don't even consider credit at allPrimary, Secondary, or Tertiary Market?