@Dax Squillante Non-debt related is everything else, which would include to name a few, insurance, taxes, management, lawncare, shared utilities, repairs, maintenance, vacancy, etc. As a general rule, most investors use ~50% for quick numbers. I personally have six (6) duplexes, and self manage and my expenses range between 25%-35% (with 25% being on new build properties for the first few years). If I had them managed, that would easily add 10-15% to the expenses.
I think if you actually itemize all of your costs, you will quickly find that a $250k duplex with rents only $2k a month to be a marginal deal, and a bad deal when you try and finance 100% of the deal. I would not personally look at that deal past the price and rents. I am a firm believer in the 1% rule (gross monthly rents should equal 1% of the total price of the property) as the floor for any deal. All of my properties are over the 1% rule, and there are some on BP that want it to be 2% (which I find impossible in my local market).