Is the plumber doing vent pipes and drains as well?

one vent pipe exists and needs repair, the main stack/sewer and plumbing into the house exists, but the rest will be new. it is a down to the studs reno on an existing basement with an addition on a deep crawl. all toilets/sinks/baths/faucets are provided by us.

From what you describe, and setting aside your cost of the fixtures, I would say the rough, repair and setting the tub are about 75% of the work & his materials, maybe more.

thanks.