Costco sells what are essentially gift cards, but they call them Costco Cash Cards.  You can buy them with a value anywhere from $25 to $1,000.

What makes them really valuable however, is that if you have a Costco cash card with any value on it whatsoever, you can shop at Costco without a membership.

How can you get them?  Have friend with a membership buy them for you, or some of the gift card resale sites carry them.

Incidentally, people selling these cards on Ebay obviously know about this benefit.  Otherwise, why else would they be selling these cards at more than their face value?