If you buy gold, better buy collectible coins, not bullion. In 1933 the government confiscated all the gold with the exception of "antique" coins. Had they wanted to, they could have collected them as well. If posessing gold is made illegal, it will have little value.
I recommend buying food. If our economy totally crashes, and it is most likely going to, that will be the most valuable commodity. (I'm only half kidding).
Truely, the only valuable asset is one that you can see and touch, (like land), as long as you don't have to sell it in a hurry.