Without meaning to tell you what you already know, SG, let me add the following.

When mom & pop start buying gold as evidenced by Costco entering the market as a seller, we are either at the very start of an investment boom in the market, OR THE VERY END OF IT!  My educated guess is the former.

Anyway, more money is to be made in precious metals mining company stocks than in bullion.  And that carries with it less risk as related to theft or cost in regards to storage fees.  Everyone should hold some bullion, IMO, but it should be a small fraction of what is held in stocks.  Furthermore, I would recommend staying away from collector coins - except as a hobbyist.  Those cannot be as easily traded as bullion when one needs coins to buy groceries or pay for car repairs.  For that matter, recognizable bullion coins are the best for an emergency "stash", and I'm sure that Cosco will not be carrying those.  

The best option for that, IMO, would be bags, or partial bags of silver coins available at your local coin dealer, or on Ebay or Amazon.  I last bought some on Ebay back in March.  I like Ebay or Amazon dealer options because one can see how long those sources have been in business and their customer approval ratings.

Thanks, SG.

VP