I'd say you're pretty much looking at $25-30K of extra cost of living, most of that being housing. So even with "only" $225K (lol) you wouldn't notice a huge change in your standard of living.

The car-free thing depends on where exactly you want to live. You really need to live in the core areas (most of Boston, Cambridge, Somerville, and specific neighborhoods of Brookline, Revere, Newton, and Malden) for it to be feasible.

One option is going "car light" and signing up for Zipcar or one of those services. Then you can rent a car in your neighborhood at an hourly or daily rate whenever you need one, without having to deal with the hassle of parking, mechanics, etc.