I haven't been to Costco in a few weeks, but I've *never* seen discount lift tickets there. In fact, you'll be hard-pressed to find discount lift tickets to the Vail Resorts in general. There are a few out there for Copper/WP and definitely for the smaller resorts, but I haven't seen any at Costco.

I did read about a deal for a BOGO for Copper (maybe WP, too?) by buying at least 10 gallons of gas at a Phillips 66. I'm pretty sure that deal is posted over at Epic (I'm not a member there, but the person who posted it on another forum is).