Everybody has to start from the bottom and work their way up in life — and homebuying is no exception, as far as having to get in on the ground floor is concerned, because that’s where the prices tend to be lowest.
But Unit 7 at 396 Beacon St. in Boston’s big-bucks Back Bay is an exception to the usual dime-a-dozen digs a low budget buys you. For $409,000, here you get a 568-square-foot architect-designed open-plan studio with a gleaming hardwood floor and an unusually high ceiling for a unit at …