I have had Yoks on my car from day one. The stock Avid A4, then ES100's now i am trying out the Spec-II's. The only bitch that i have about the tires is the treadwear, but i think that is due to my driving style.
Check out tires.com or tirerack.com.
Tires.com gives you free shipping, but tirerack.com seems to be like 2 or 3 cukcs cheaper. Just compair the prices on both sites and see what is cheaper.