Questions first:
1. Well maintained but how about updated? Have the units been updated in 30 years? Are you looking at 16 renovations of kitchens and baths? Floors?
2. What are the actual expenses? Does it have separate utilities for heat? You don't want to guess at the NOI even if the rents are low.
3. Are they all on leases or month to month? How hard will it be to raise rents? Obviously, you can't get market rent if the unit's are 30 years out of date.
Two ways to value the building: 1) cap rate; 2) comparables.
Yes, it's hard to find a true comp -- a 16 unit building. But you can find 4, 6 8 or 10 unit buildings and figure out the area's per unit price. I just saw a 10-unit in Fort freakin' Wayne Indiana that they want $104,000 per unit, which seems insanely high to me based on an NOI of like $60K.
But it's listed by a respectable commercial realtor and God knows every owner has the right to put whatever stupid high price on their property they can and hope for the best. Or, as my Dad used to say: "there's an asking price and a selling price."
Have you asked the sellers what price they are looking for? You said they want to put it on the MLS so isn't this an exercise in futility? They will put a big MLS price on it or it will get bid up on the MLS. Good luck. Come back and update us.
