Who knows? What the building grosses is not real helpful here. What is more useful is what it nets. Its Net Operating Income (NOI) is the money left after you subtract out all expenses except mortgage payments.
EXAMPLE: If Building A grosses $16k, has expenses of $5k then its NOI is $11k. If building B grosses the same $16k but has expenses of $7k (because its very hard to heat in the winter) its NOI is only $9k. This better represents the investment quality of the 2 buildings. As such I would expect Building A to be worth more than Building B.
What you really need to look at is what other buildings with similar NOIs to your building have sold for within the past few months in YOUR AREA of the country. With the info given your question cannot be answered. Talk w/ a good RE broker who deals in apartment houses in your area.
I am looking at a 4 unit that will generate 16,000 a year in rent, Based on that can assume the property will appraise for $70,000 -$80,000 on an income approach?