I guess it comes down to the level you are playing at.
For the average Joe (or Itsac or . . .) who plays fiddle in a country band at the Dew Drop Inn every Friday night, yer basic ebony (graphite? plastic?) bow probably works just fine - even tho' Joe can probably tell there is some difference between the way he plays and the way the solo violinist in his local symphony orchestra plays.
But I guarantee you that the two guys sitting at the bar thinking about asking that cute girl to dance can't tell the differrence (and don't care that there is a difference!).
So a soloist who was born in Munich, trained in Milan and is now principle violinist in the San Francisco Symphony will demand the very best quality. Because he can tell the difference.
Could he play with the same bow as Joe at the Dew Drop Inn?
Of course - but why would he, because it simply can't perform at the level that he requires.
As for the bow's components being 'easily obtainable', check out this site:
http://www.smithsonianmag.com/smithsonian/issues04/apr04/violin.html
My opinion is that someone performing at the highest level requires the very best equipment to do so.
It's always seemed to ridiculous to me that Formula One racing teams spend so much money - but I guarantee you that they buy the $28 titanium screws because it helps them go faster.
Why do recording studios use Neumann mics when an AT 4033 will do the job just as well for a minimum of $2,000 less? (flame me now you mic-heads

)
Because they can tell the difference!
In my business, I use $17,000 Huxley roulette wheels because they perform marginally better than the $3,000 US-made wheels.
Why? Because I can tell the difference and I want the best .
If you can't tell the difference, then buy the cheaper one and have at it 'cos it's not going to make any sense to you that someone will pay so much more for something that you cannot see as being better.
But if they can see a difference, then they are happily going to pay more.