I'm considering buying my first commercial-sized apartment building in Lincoln (a purpose-built 8-plex built in 1926).  It doesn't need much work. What sort of cap rate should I expect to see on something like this?  How would I go about finding the typical cap rate for my area?

My realtor just told me the other day he has been using 6%.

Only the cap rate & gross revenue determine the final value, just like comps would for a SFR, right? If the property needed a ton of work, the cap rate wouldn't change, but the selling price would have to be adjusted accordingly, right?

When purchasing you should look at the property as it is now, currently. If there are 3 vacant units and the NOI is lower you shouldn't base your numbers off of an NOI at full occupancy. You are correct, it is all based off the NOI nothing more nothing less. Take the NOI divide by, in our example 6% cap rate and that should be your number but you still must consider other factors like capital expense (roof, sidewalks, etc...) but the starting point should be the NOI/cap rate. Not sure if this helps but this is how I look at it.