Four doors in a town of 4,000 or two doors forty minutes from a job center

Your point about correlated vacancy is the whole thread. Four units in one building are already correlated on the roof, the boiler and the parking lot. Add one employer and you've stacked a fourth correlation on top. That doesn't make it a bad buy, it means the eight cap is paying you for something specific and you should be able to name it.

The question I'd want answered before anything else is what the last downturn did to that town. Not the state, the town. If the plant cut a shift in 2009 or in 2020, somebody local remembers what rents did and how long units sat.

@cairn is asking the right question and the assessor's site will half answer it. Look at how many parcels changed hands in that town in a bad year and at what direction the assessed values moved. Sale prices aren't public in every state, roughly a dozen don't disclose them, so check whether yours is one before you build a story out of thin data.

Different angle. With four units at 575 you're screening four times as often for tenants who have less margin, and in a town of 4,000 your applicant pool for any given vacancy might be two people. I'd want to know how the current owner has been filling them before I got excited about the cap rate.

@hollow, who manages it? You said you've owned in small markets so you probably already know, but a fourplex at 185k generates maybe 2,400 a year of management fee at ten percent, and nobody licensed is driving forty minutes for that. If the answer is you, forever, then the eight cap has your labor priced into it and it isn't really an eight.