I've worked in a converted parking garage office before, so it must be at least somewhat economical. It was kind of awkward; you could absolutely tell that it used to be a parking garage. but it was completely functional.
As an employer I'd have liability concerns about embedded gas fumes and long term health effects - but the arrangement of space does work better for office work - since large rooms without natural light are more common place and internal rooms (like conference rooms or staff rooms) wouldn't have locked doors between them and windows in case of a fire.
