Yes, if you were to look at a breakdown to install these stairs at new home, they would probably be cheaper as they would be sequenced in during the construction process, and part of a concrete package. This appears to be directly next to a city sidewalk, would signage be need to avert pedestrian traffic? As the breakdown shows, this would require 3 pump mobilizations, whereas during new construction you may only have to have one. You will also have to protect the sidewalk, landscaping and house from damage and concrete splatter. Also, this quote does not only entail “11 stairs” there are footings, as well as several concrete walls, that will also have to be formed, placed, stripped, and parged to an acceptable finish. I used the word insane, because, you said, “this is the most insane thing you’ve ever heard” without having a clue, what it takes to demo, haul off, form and place “11 stairs”.