Since this must be to develop a budget, using the figure of $900.00 per fixture should put them in the neighborhood. This would not include water and sewer to the site, and would also change if they went to other than competitive fixtures.
I dont know about USA. I have worked in the plumbing industry carrying out Installations & maintenance on Domesti, Commercial, Industrial- Plumbing Drainage, Gasfitting, Roof & roof plumbing for the last 39 years since my Apprenticship. I know there is a degree of difficulty to be added to any job pricing. For example roughing in a cottage in a residential subdivission as against working in a shop front situation in a small town as against working in a inner city shopfront, where parking & proximity to the workplace will differ tremendously. If you are truly trying to get a professional bussiness plan together – get 3 quotes from reputable Licenced Master Plumbers in your area. this will give you a real indication of your upfront costs, but please don’t stuff the contractors around, get professional plans for them to work to.