Here are some of the assumptions I made:Commercial loan with 25% down @5.5% for 30 years. 

My laymen assumption is that the nicer the school district, the higher the property tax which ultimately hurts ROI.

Zero coupons are 1031 compatible products that do not pay monthly income but are assumption of debt for a value add project that let's the 1031 investor park debt in exchange for a payout later rather than mail box money today. 

My assumptions include the following: 8% vacancy (equals 1 month of vacancy), 10% for property management (didn't know if you were self managing or not, but it's always good to put in just in case you decide you do want to get it managed), CapEx and Maintenance of $1500 per year, insurance of 1200, taxes at 3500, I assumed you would be paying no utilities, that those would fall on the tenant and that you would be borrowing the 15K for the cosmetic updates, so I added that to the base mortgage amount. 

My question - do you think its worthwhile to get someone who is licensed (and pay the extra $1000 - piece of mind) or try some of these other guys off of facebook, craigslist, etc (WITH the assumption that their references and insurance checks out).

.  +$1000Add some insulation $500.If you can nail a few of these assumptions down that are big, then you'll be able to get a good price.  

The work to make sure their assumptions are correct goes beyond what we can do here on this post.The proforma is the most important tool that we have to assess any project.

They have a listing agent involved who will probably try to kill the idea of seller finance, but that's an assumption on my part.I didn't know if creating an LLC with the sellers and buyer as members, bringing the assets under the umbrella and then allowing to the buyer to buy the sellers out would work. 

We haven't talked about the details yet, but I am under the assumption we would both like to do this extension outside of VRBO.He stated that if we are to extend his stay, he would prefer to pay us at the beginning of a month, for each month he will stay going forward, instead of paying one lump sum like he did on VRBO.

However, we did brainstorm the following offer scenario:Owner-financed at $140k @ 5% APR with 3% down, plus $10k rehab (so ~$15k out of pocket) based on the assumption (and negotiating angle) that it would have to be switched back to a 3-family (and therefore we only counted 3-family rents).