Graphics card manufacturers typically overstate PSU requirements in the often vain attempt to counter the liar-labeled junk out there, like Raidmax, Logisys, Apevia, Diablotek, and even CM. Look at the power consumption chart in the article and you will see that the 450W PSU was plenty for the card.
Yea it will work the $500 build uses an efficient psu, like the above poster stated, quality is everything with a psu. Speaking of CM, I had a 500w Coolermaster psu in my first rig I built last year and it died within 2 months.