I just tried that link and it failed. Going to tires.costco.com and doing the search for SRT6 tires showed the Michelin 255/35x19 Pilot Sport PS2 for $277.99 each.
MikeR
You are right, the link I enclosed won't get you there. But if you drill down from the following link you'll still see the $119.99 tires!
http://tires.costco.com/