A haircut takes nothing more than a pair of scissors but if you want to come out of the shop looking like <insert favorite movie star here> you'll probably want to go to a stylist/barber with some experience and the appropriate tools.
These seems to match your component spec: http://www.nashbar.com/webapp/wcs/stores/servlet/ProductDisplay?partNumber=VL-CLC&catalogId=10052&storeId=10053... 300euros retail, now on sale for 150euros.
You can get your spokes for $20/wheel... or $100/wheel: http://www.wheelbuilder.com/sapim-cx-ray-spoke.html
Maybe on the higher end the manufacturers are looking to cover the cost of R&D (design, fatigue testing, wind tunnel testing, engineering expertise), the cost of doing business (marketing, human capital, distribution, etc.), and the cost of actual fabrication (human hands, machine building, or a combination of both)?
And finally, what is the market willing to bare... a little profit perhaps for that fancy new car, the kid's college education, or a tasty pack of western cigarettes? If people keep willing to throw more money at products why charge less? It's the beauty (and ugliness) of a free market.
Then again I cut my own hair with a pair of clippers and have no formal training as a stylist (or wheelbuilder) so you probably don't want me to cut your hair (or build your wheels).