Finally, I occasionally buy things for a rental on Facebook Marketplace.

I see them on Facebook marketplace constantly for ~$300 for a well working set.

I didn't find any challenge finding quality tenants by posting on FB marketplace, roomster, roomies, basically all of the websites. 

I just advertise on Zillow/ Hotpads/ Facebook Marketplace etc. and use a background check website.

My rent data is also based on CoStar and other social media outlets' marketplaces.

I posted on FB Marketplace to check demand and was able to find people interested in paying $1200 for 1800 square foot garage.  

There have been one or two platforms that claimed that their goal was to eventually create a marketplace for investors to swap out any deal with another investor.

Nobody wants to go to jail for a stupid crime that’s obvious to detect.

FB marketplace, join all the real estate FB groups for your area, REIA meetings, real estate meetups, talk to agents, get on Zillow and look for properties that look rehabbed/flipped and find out who sold it (the seller will be the investor you're looking for) and ask them if they want another hot deal in the same area.

I would also prepare to sell it on the used marketplace but if you absolutely don’t want to go that route then I would recommend getting it included in the purchase upfront (but still use it as a bargaining chip first).3) marketing: the best target audience is going to be a savvy house-hacker for a property this style.