Trying to figure out some creative solutions for a potential opportunity.

A cash offer isn't an acceptable offer for them and they may or may not list it with me. They had a bad experience with a realtor in the past although they didn't completely shoot down my value proposition. They did seem interested in hearing more about a creative financing option and want a proposal. 

The property is a zero lot line. In other words its half a duplex. These make great rentals and are super affordable housing that sell quickly in our area. The floorplan is a 3/1.5/0 and is about 1,200 sq/ft. Most ZLL's in our area are 2/1/0 and about 1,000 sq/ft so this is a deluxe model. LOL. It is in an area that is desirable and has more sought after schools so that's a plus as well. 

The seller wants to net $205k. With a list price of $220k and a 7% cost of sale, it would net them about what they need. That would be maximum value if it were listed. I expect it might get that but I would be confident in them netting $200k. 

They are currently paying $500/month on the mortgage and about $300/month for utilities. Market rents would be $1,250 to $1,300. 

I'm wondering what would be the best way to structure a creative financing deal since it seems like this one might have some legs. I was thinking of offering the owners $800/month so they would be making $300 after paying the mortgage. They currently have the $800 expense but don't want to deal with tenants. I would fill the unit for a small premium over market rents with a tenant that would purchase it. They would pay $1,400. I would be able to keep $600 a month. The seller would be locked in at $205,000 and I would lock the buyer in at $220,000 maybe. After a few thousand dollars of closing costs I would be able to profit a little more than a regular commission but close. 

Any thought's on this? I'm trying to wrap my head around these types of deals. Thanks in advance!