Sorry I don't speak about "Wiring board" but boards which was used for Wiring development,(started at Ivrea, finished at "Universidad de Los Andes" Colombia) and released in 2004, one year before arduino.
I "think" those boards were probably Atmel demoboard.
If you to speak about Wiring board I agree with you it is cheaper (about 45 $) but 644 is more powerfull that 328p (UNO)
Barragan has not exceptional charisma of Banzi and Wiring project was stifled by Arduino.
The Wiring project remained confidential and boards have not been manufactured in quantity and therefore the price was expensive.
It's domage because the 644 is a good micro.