Is it ok for me to not get a killer deal when buying my own home?

[NA Loraine Nielsen]

Here's the thing: I'm thinking about buying a house that would make a great rental if we need to move out of the area (which is somewhat likely). I used the Rental calculator to see how the numbers would crunch. 

The house is only 2 years old, 1260 sf, 3 bed, 2 ba, 2 car garage. The current owners are friends who told us they are getting ready to sell and asked if we wanted to make an offer before they list with an agent. It was super easy to find comps because 6 homes sold on the same street earlier this year, though they were all older (2008-2012). The closest comp was built in 2012 by the same builder, same sf, probably the same floor plan, and sold in September 2016 for $165,000.  Our sellers have told us they would go lower than that since there won't be a RE commission.

If we get them to accept $160,000 with them paying all of the closing costs, the expected rent will nearly cover the mortgage, a 10% vacancy cushion, and a 10% property management cushion. So, not a stellar investment with no real income expected if we need to turn it into a rental. Is that okay when we're talking about buying a personal residence? Especially an almost new one? I'd love to hear what you think.