At what point does this 4 plex make sense?

[Illini1]

I have never done anything like this before and I am looking for some advice.  A four plex near me has attracted my attention in suburban Chicago. All units are 1 bedroom and 1 bath.

List price = $174,900 (Sold for $350,000 in 2006 and came on the market in April for $192,000)
Property Taxes = $6,000

Fully rented in a decent working class neighborhood across the street from a large manufacturing facility.
I don't know exactly what the rent is but similar 1 bedroom and 1 bath apartments in the same town are going for $750-$800.

The listing states that it has a newer roof,AC,sliding doors,freshly painted & has large rooms.

I was figuring at $170,000 purchase price with putting 20% down and at 4% interest my mortgage + property tax would come to $1,149 per month.

At what rent if any does this make sense?  Is there something else that I should be considering?

Any and all input would be greatly appreciated.

[snacky]

why is the seller taking such a huge loss on the property? people don't do that for fun. is there a huge problem with the building, or something else? find that out before you take on someone else's problem.

[Illini1]

snacky:

This seller bought it in 2008 for $160,000.

[zephyr911]

If it's fully occuped with no major repairs looming, it could be a good cash-flow property. $750 per unit would be 1.71% of purchase price... $800 would be 1.83%.
Some landlords here get up to 2% or even a bit more, but they tend to be high-maintenance properties. I'm happy in my area if it's 1.5% and isn't falling apart.

Paying your debt service on an 80% mortgage with less than half the expected rent is good. Our successful rentals have debt service requirements around 40% of rent. As long as we're careful to keep costs down, they cash flow just fine.