This is how I would look at it
Income:
(A) Annual total income from rents = $14,400
(B) Annual Additional Income (laundry) = $240 (estimated)
(C) Total Annual Income = $14,640
Expenses:
(D) Annual Taxes = $2,520
(E) Annual Electricity = $0
(F) Annual Gas = $0
(G) Annual Sewer = Unknown (do you have this info?)
(H) Annual Water = $1,500 (Depends - should check sellers previous water bills)
The following expenses depend on what you want to budget for/what has been previously seen by the seller over their ownership history. Based on that information, the percentages can change. I just put in what I typically use (except for property management which is known)
(I) Property Management = $1,008 (7% x A)
(J) Maintenance = $720 (5% x A)
(K) Vacancy = $1,464 (10% x C)
(L) Collection Loss = $72 (0.5% x A)
(M) Capital Expenditures = $720 (5% x A)
(N) Total Expenses: $8,004
NOI = $14,640 - $8,004 = $6,636
Value = NOI/Cap Rate
Depending on the area, you'll have a different cap rate
I use this rule of thumb for estimating cap rate based on property "class":
A = 6-8
B = 8-10
C = 10-12
D = 12+
So the value at 8% cap rate for example would be
Value = $6,636/.08 = $82,950
With smaller multi-families, looking at comps is appropriate too I think. So you could probably see prices from 80k to 100k for similar properties. The rest comes down to what works for you and what you want.
I'm interested to see other responses also.