There is another metal though, one that is precious because it is so functional. I'm talking about steel, specifically in blade form. Knives are the chief and king of survival tools, with a value far beyond their weight and cost.
The subject of knives as trade goods is a matter of much debate amongst the BCP family. Some worry that they may be handing over a weapon that can later be used against them. Some are reluctant to give up a tool that they may need later. Others are fully in favor of trade, seeing yet another benefit of the knife. None of these parties are wrong, even though they disagree. Let's address these views to find some understanding and come to informed conclusions.
I may be giving up a weapon
This is entirely true. In my home, though, we have other, more effective weapons. It is in everyone's best interests to acquire, train with, and employ the best defensive options available. Also, if I suspected a person would turn on and endanger me or my tribe, I wouldn't trade anything with that person, short of sheer desperation.
I may be giving up a tool I'll need
Never trade your only knife, unless you're truly desperate. Never trade your spare knife, if you can avoid it. After that, as long as your personal knife needs are covered, your risks of being caught high and dry without a blade are greatly lessened.
My knife has value as a trade item
If you've arrived at this conclusion, it becomes time to consider keeping a few extra blades around as trade fodder. (If you've arrived at the opposite conclusion, learn to identify the traders, because a source of tools is never a bad thing.) As a side benefit, between the time you acquire it and the time you trade it, you possess a useful tool. This is always a good thing.
What knives for trading?
It stands to reason that the ideal trade knife would be inexpensive, with obvious tool value, and minimal apparent weapon value.
The obvious answer to that is the Mora. It's collectively one of our favorite blades for many reasons: they're large enough to do all sorts of useful work, without being so large and stout as to scream "stabbing stick"; they take and hold an edge well (Erin can confirm this); and they're inexpensive enough that you can keep a couple around without blowing most budgets.
Whether you choose to barter with blades or not, it's an important consideration to have, and to keep in mind. Someone will always be willing to trade, so keep your eyes peeled, stay sharp, and you can stay ahead of problems.