I checked your with quotes vs one i got for my house (You can check mine in one my posts here) seems fine, i mean there are few thing which my contractor has put more but few things where he has put less compared to mine. but at least your's look little less than mine
I was speaking to contractor and he did mentioned that he can always quote less and can make 100 way where without even a smallest hint he can make money (and i believe o this

as i write this there is major change which contractor suggested after starting excavation, and it was easy to get everybody working since they already know each other
regards
Raghu