What's the current price premium for new construction duplexes?

[Kavi S.]

I'm looking at a new construction duplex right on the 495 belt (+/- 1 mile) and I think I'm going to throw an offer down. I'm looking at it for an exercise in house hacking, having graduated from my 3-family in Boston. 

I spoke with the seller's agent directly who informed me they just rejected an offer 7% below listing and they're not too concerned to keep rejecting until the building is move in ready. I was thinking of coming in around that region, not sure if I'm swayed, I was talking to the seller's agent after all - her best interest is probably a listing price offer. (Negative tone not intended - she's been very helpful!) 

My 3 family in Boston easily hits the 2% 0.7% rule. I'm not an expert, but I think that's decent inside of Boston. This building would be 0.64% at the current price and market rents. I could probably hit 1% in the same area, but in a 100 year old building with dozens of hidden problems. I'm thinking that lower ROI might be worth the lower frustration; this isn't my day job. I somewhat vetted the builders and they do good work, the building is well designed by a real architect, and I actually have a bit of a thing with the area it's in. (ok fine I'll admit I like it a lot)

Building 2 miles away is built in 1850, has additions in every direction configured like a circus fun house, 1 unit of land, $156/sqft, 0.55%er

Building 4 miles away is built in 1900, half renovated, 0.5 units of land, $199/sqft, 0.60%er

Building 0 miles away is built in 2019, no funny stuff, 2.5 units of land, $204/sqft, 0.64%er

So I'm starting to think it's worth the price. The seller's agent is certain it'll appraise appropriately and the loan won't be an issue. Do I need some sense kicked into me? Am I about to pay a premium?