Need help stat for deciding on a deal

[Lucas Mills]

I'm currently in negotiations for my first property.

The owners live in one side of this duplex and need to continue living their until Aug 31st. With closing date of June 1st, my first mortgage payment wouldn't be due until Aug 1st.

At 112k, the owners would like to live for free until Aug 31st. This would mean one month of mortgage/insurance payments at about $640 that I would be paying without a paying tenant.

Or, I could pay $115k for the property and the owners will pay me $400/month for rent until Aug 31st (potentially 3 months but they may only need 2). This would be up to $1,200 in rent. However, at the higher price of 115k, my monthly cash flow is reduced by about $14/month.

 I know that what's better is very subjective, but I'll say this: my current goal is to achieve 3k in monthly passive income within the next 5-7 years. So on one hand, my brain is in "highest cash flow" mode, which would mean going with the lower price and giving the owners free rent for 3 months at a cost of $640 to myself.

On the other hand, I can see how $800 - $1,200 up-front would be helpful, and to sacrifice $14/month in cash flow doesn't seem terrible. I am having a difficult time weighing the pros and cons of the two and making a decision -- looking for some opinions.