You may want to confirm this but I heard that if you have a Costco gift card they'll let you in and use it as a membership card.
Here's a link that mentions it too:
http://www.huffingtonpost.com/max-levitte/10-ways-non-members-can-shop-at-costco_b_9399312.html
I'm not a big fan of costco myself. Some of the stuff you mentioned, like the meat, is expensive overall. The quality is better and combined with the portion, makes it more money than I'd normally spend on it.
But even with that I think that the savings still pays for itself based on what we do get from there.
Maybe you can try the gift card and see how you like it.