I'm exploring all options at this point including finishing the home with other builders, as well as selling what has been built (slab and block walls of a single family home 4 bed 3 bath) to another builder or investor.Does anyone have any recommendations on where to look for potential buyers for something like this?

If you can't find what you're looking for, try the Bigger Pockets Fileplace.

However after talking to buyers I am unsure since the 50k downpayment seems unattractive to alot of them.  

My advice would be try and find a reputable investor friendly Realtor in the area 1st and foremost.

Quote from @Sara Kumar: Go to YouTube and search for "real estate negotiation training," and you'll find plenty of videos.

With time as your main deployable resource right now though, take that time to learn as much as you can until you find a path that sounds both realistically achievable with your current resources, as well as something that sounds interesting to you.I'm always happy to connect with other investor folks around the Twin Cities, so feel free to shoot me a message on here if you want to chat directly! 

My question is, what type of agreement do we need to get this deal locked in (I thought my BP Pro membership would have some agreements, or something - not finding anything)? 

Have you thought about how long-term rental loans can help you achieve consistent cash flow and build wealth over time?

I have made strides to help another investor find deals as well as take my own down. 

HELOC, cash out refinance?