I'm trying to put together a build for my dad's RS2. He lives on a 20% grade, so needs a triple. I already have a set of wheels and a saddle. Also, we're talking about an extremely meager budget.

I have 105 on my Allez Elite and it's great, so I started there. The 105 group, with a triple, is $660 at Team Cyclist. That seems high to me, and I still need to get a stem, bars, headset, seatpost, and seatpost clamp. So I thought about this: Mercier Corvus $796 @ bikesdirect

105 shifters
ultegra derailleurs
cane creek brakes
fsa gossamer megaexo triple
shimano 5600 12-27 cassette,
cn-5600 chain

and in addition, you get:

double-butted aluminum frame
carbon fork
shimano hubs and rims
velo road saddle
FSA carbon/alu seatpost, and ritchey stem
ritchey bars
clipless pedals
michelin dynamic tires

Can anyone explain to me why groupsets are so pricey, but fully-equipped bikes are dirt cheap? How can this be? Why aren't these bikes stripped down and sold part-wise for profit until the groupset prices come down?