Living Social has a Costco Membership deal.
The price ($55) is the normal price, but you get a $20 gift card to use in store as well as a coupon book that has a bunch of freebies like a free (obviously Costco sized!) pack of AA batteries, rotisserie chicken, case of bottled water, etc.
And as always if you're not happy with your Costco membership you can ask for a refund at the membership desk!
I know there have been Bees who have asked about Costco memberships in the past, so hopefully someone finds this helpful.