Costco are doing a repeat of this deal as a Mother's Day promotion. The promotion is in-store only and ends on Sunday 8th May. You have to be a current member to purchase.
Confirmed from the previous deal these have no expiry and can be used to renew your own membership.
@bwatt72: For you, it would be a $120 spend (= 2 years of membership) in order to obtain that $20 gift card.
If you know a mate who is already a member, you can pay them $40 to become a member and they keep the $20 gift card.