Have a friend who is a Costco member buy you a Costco Cash Card and fill up at the Costco gas bar without a membership
also Cash Card can be used in store twice a yearThe gas station is open to Costco members only, with one exception: Costco Cash Card holders do not need to be members
* Non-member use
You do not have to be a Costco member to use a Costco Cash Card, but non-members must register for a one-day shopping pass at the Membership Counter to access the warehouse. Non-members may only be issued a one-day pass twice per calendar year and the one-day pass may not be used as a replacement for a Costco membership. Non-members may not carry a balance on the card. If they do not spend the full amount of the card, the balance will be refunded at the cash register. If the value of a non-member purchase exceeds the value of the cash card, the excess can only be paid by cash, debit or MasterCard.