Is there a collective name for the non-groupset parts? I would like to estimate the price of a bike if bought in parts.


One thing is the frame, that is easy.
The front and rear shock can also easily be checked out as individual components.
Tires
A groupset seems to include:


brakes
shifters
drivetrain
BB
hubs.



Those categories are easy to check for price on the manufacturers sites. 



However, a few pieces remain:


saddle
stem
bars
grips
seatpost
spokes
rims
axles
pedals.


IMHO those peaces constitute a small, but significant fraction of the price of a bike. However, they are so numerous, that checking their prices is tedious, compared e.g. to googling "Alivio groupset" or "Schwalbe Rapid Rob".

Is there some easy way, given that I know the prices of all components in the numbered bullet points above, to estimate the price, in parts, roughly, of a bike?
I don't think there is an 'easy' way so it will require a bit of leg work and study to get a good reference. It is unlikely that any manufacturer will offer any of these parts at a higher spec level than that of the groupset. So I would:


Choose a few bikes at different spec levels (based on groupset, Acera, Alivio, Deore, SLX, XT and XTR (or equivalent SRAM models)).
Jump on to BikePedia and note down what parts each bike has.
Use Wiggle or Chain Reaction or similar to price the parts.


This will give you some reference as to the price of all the other parts on any bike you are looking at by the groupset. 

It's also worth noting that:


under SLX level most bikes will have generic parts so take an estimate at quality based on materials.
bike companies are buying thousands of these items so with economies of scale will actually be paying very little.
unless you are buying factory wheels separately you will have to pay for building.
bikes cost more to build than buy complete but you get to choose what you want.