@Ian Livaich definitely a case of analysis paralysis! That is ok though! We have all gone through it.
While running the numbers is crucial, perhaps the most crucial piece to buying a rental property, you cannot ignore variables of this kind. For instance, yes run the numbers including the price of a PM because you want to be safe. However, if you're current situation allows for you to not have this PM cost as you will be self managing - review both calculations (with PM vs. without PM). At some point, you will want to break away from self managing and it's vital to know where those numbers are. On the other hand, you also need to be prepared for the exact situation you could come into - which would be without paying a PM.
This holds true for other items as well (tax & insurance increases, repairs evaluations, etc.). Prepare for the worst (i.e. highest payments) and once you're prepared see where you have room to adjust anything. If its a good deal including a PM payment, it will be a better deal without it.
This is a big step to get over and I can tell you first hand that you won't until you actually buy a property. BUT since you've done your research, talked with fellow investors, & run the numbers (countless times I'm sure) - you'll notice it's actually not THAT big of an investment because you are prepared for the managing of it, financially, professionally, & personally.
Good luck! You'll get a good one.