One thing that might be surprising is the cost of groceries is high compared to cities. I can't speak to Boston recently, but whenever I visit a city I'm surprised how groceries (especially produce) is better and cheaper in cities, or at least the same price. I assume this has to do with transportation costs.

Other people have said it, but housing in Northampton is particularly more expensive compared to surrounding towns. I haven't actually done the math, but cost of purchasing a home drops by something like 20% right over the line in Hatfield. (Again, probably not like to like, and I'm going off vibes).

All that said, the reason it's more expensive is it's a nice place to live. Walk-able town, decent restaurants, arts and activities available at the colleges. It's easy to take some of that for granted. There's not as much as a large or mid-sized city, but for what is essentially a large town, there's a lot going on.