Hi @Seth Cunningham ;
Fourplexes are going to be classified as residential, so having comps will be most important in evaluating it.
Someone said it above and I have to strongly second the thought regarding deferred maintenance. Figure that out going in. My experience with purchasing and owning a fourplex has been (and it has deferred maintenance) that you may need - sometime significant - cash going in to fix a bunch of issues up front. You can't rely on the operating cashflow to get you there. The tenants in these buildings seem to be much more transient and I don't count on them paying all their rent every month or staying the entire lease. This is a big assumption with a C neighborhood if that's what you are looking at. About half of them will pay rent well, the other half not so much. If you can go in and rehab it and make it the nicest building on the block, maybe you can upgrade your class of tenant. But check out the neighborhood. You may be stuck with what you have. I would find out how long those tenants have been there and the rental history of the building.
Some folks use $100 a door as a metric for multi. I like this too, if not more, as it provides some contingency $. You will have a water heater go out, or an a/c unit break, or plumbing leaks, etc. Have a sufficient cash reserve. The first 6 months may be a drain before making any money.
If you are working 12hr shifts I would question PMing the building yourself. Multi has much more TLC required. Tenants call to change a light bulb. Not kidding! My PM is over there all the time for something, usually the garbage disposal. I think they put rocks in it. They are hard on apartments and equipment.
Well, not trying to discourage. It's not all bad; just my experience and lessons learned, and I hope it helps in your decision-making. Your numbers are in line with what I came up with. But it depends on what financing you get. I like this guideline that it should cashflow to your criteria assuming it is financed at 100% (so says Ben L). That puts you under $200/mth on this one. If you go hard money, it may be negative. If you go conventional, you are ok (25% down), but you don't want to buy cashflow either.