I really get annoyed when your complaint that NASA uses those expensive and exotic parts- what do you suggest build it out of wood tinkertoys? Space is a demanding environment, and not one where you assume "well if off the shelf is good nuff down here then its good nuff for the space station"! Stuff built to withstand large thermal oscillations, radiation, and hard vacuum is by definition going to be exotic...and yes its going to cost more than driving down to ace hardware and getting it there.

Let me give you an example... I built a vacuum system here on earth...it didnt have to take wild temp swings, or radiation, and no lives depended on its functioning perfectly all the time. I had to have a few meters of wiring inside this chamber...I was shooting for a base pressure of 1*10^-10 torr, (~1/10trillionth of an atsmosphere), so I tried using off the shelf wire ultrasonically cleaned with water and methanol...I insulated it with glass beads...not good enough...I ended up spending a pretty penny for special silver plated copper wire insulated with Kapton.
You cant use regular screws for hi vacuum work either- they create trapped air pockets, you use "vented screws". You cant use regular copper either, you have to use oxygen free copper. For insulation you use vacuum compatible ceramics-Maacor, or alumina...neither is cheap.
The point is I had to go to great lengths and I was doing nothing NEARLY as demanding as building something that was to operate reliably in space with ~0 maintenance!
You can be sure that the scientists at NASA are quite aware of budgetary constraints...how long has it been since NASA was rolling in dough? But they also know the criticality of trying to get it right the first time...ESPECIALLY if lives depend on it! So if they use a screw that costs 100 times what one designed for earth conditions does I am not going to whine- and I doubt the astronauts whose lives depend on it are going to complain much either...
This IS _BY DEFINITION_ rocket science!

-Robert L.