If you work with the right company, they can find you a property which is in a good neighborhood with good enough renovations so you don't have to worry about cap ex, repairs and vacancy for the first 2-3 years.

What are the cap rates like in your area?

If you don’t know Saint Paul just passed a 3% rent cap and Minneapolis passed it so the local government can implement a rent control in the future.

Cap rates are terribly compressed because rents are generally pretty sticky and lag behind real estate prices.

Here’s one that might throw you for a loop - Reversion Cap Rate.

In situations such as this, if it's a multi-family, an appraiser might use Gross Rent Multiplier and/or CAP rate and compare to other large multi-family properties in the town/city/area code. 

There are multiple ways to come up with a cap rate, so be sure to always ask how it was calculated.

And your repairs will likely (again, likely not definitely) be much less than for older homes.Knowing what I know, I would probably put 200/mo for repairs and cap ex and 100/mo for vacancy/collections and you should be about right - at least for the next 5 to 7 years.

Repairs/cap ex of $75 is way too low.  

You'd be lucky to buy one for a 4 cap, and your financing cost is going to be higher than that.