Cost of Cockpit Instruments

Hi All,

I am a student for my private license, and during my last ground
school session, I was having discussion about how glass cockpits might
be made cheaper by using commoditized components. For example, some
GPS units cost $1000's US, but a friend of mine help found a company
that made the most advanced GPS receivers around, and those devices,
including package, barely cost $400. Simpler receives are a lot
cheaper, some as low as $50US (http://electronics.pricegrabber.com/gps-
receivers/p/2003/form_keyword=usb+gps/rd=1) I'm not sure what the
differences are in receivers, but I would imagine that a "good" GPS
unit could be had for say, $500, in which case, that, coupled with a
conventional PC and software, should be able to do anything that the
fancier (Garmin, etc) units can do. Most importantly, that one PC
could work for many instruments simultaneously, and cost difference
should be huge . [Yes, I know, reliability, FAA
certification...yada...]

What shocked me was the purported cost of instruments compared to what
they could cost. A USB pressure sensor should not cost more than
$500, in my opinion. I guessed that the VSI might cost a few hundred
dollars US as a conservative estimate. My instructor and another
student stated that the cost is more like in the $1000's for a typical
instrument. Is this true? It's not that I doubt my instructor or my
fellow student. I just want to get an idea of how much these various
devices cost.

For a base reference, I would consider the standard instruments found
in Cessna 172.

All comments welcome,

-Le Chaud Lapin-