If you have the fixtures AND the plumbing is all in correct place (say doing a replacement with new fixtures) toilet install is about $100-150, sink at same time probably similar amount assuming it fits the countertop cutout, shower can run from a low of $1000-2000 for a simple "drop-in" or free-standing prefab (Ughh) acrylic or fiberglass unit that fits the rough opening, to more like $3000-5000 commonly for economy shower and more like $5000-10,000 for somewhat highear quality with good tile job say.
If you need the piping modified as well - so say converting other space into a bathroom, here are a couple of previous similar questions with answers which might help:
https://answers.angieslist.com/what-c...
https://answers.angieslist.com/how-co...
I won't even ask why you are looking to install these in a new house - why they were not put in by the builder - unless they were stolen after you took possession of the house but before you moved in, for instance - in which case sounds like time for an insurance claim.
