First time Rental property advice

[David Chase]

Looking for some feedback and thoughts on a potential rental property opportunity.  My parents currently rent a house from some other family members that I could purchase and continue to rent to my parents. The relationship with my parents is good. They are 61 yrs old would probably rent this property for the remainder of their life. The property doesn’t need any work has a newer roof and furnace. They currently pay $850 month and pay their own utilities After Principal interest taxes and Ins I figure about $250-$300 month in extra income. If I factor in cap ex expenses that would be another $100 roughly. My question is after taxes on that return is a smaller return of $150 A month or so worth it? There would limited risk, they pay on time won’t have any vacancy issues my dad has been handling all the small maintenance things. Any insights would be helpful. I’m not sure what sort of returns problem usually expect from rental properties 

Thanks