I've read and seen a few commentaries of survivalists/preppers/etc. turning their noses up at the idea of barter. There stance is that the only things that people have are the baubles of a consumer society that would be useless PSHTF. Their stated belief is that the only things that you (for example) will have to trade are things that would no longer be useful, or that everyone would have, and vice versa, and so there's no point trying.
A few will raise the problem of exchange rate; whilst Currency and Money are abstract ideas - they don't mean anything in and of themselves, they represent a common way to trade and exchange goods. One of the reasons that we are heading towards a major financial crisis is that Money has become a goal in and of itself, rather than remembering that simple point.
Well, there are many bartering schemes around (look up LETS) - a person (or group) would do themselves good to start looking into such schemes. Exchange rates, yes, can be difficult, but not impossible - humans made do for thousands of years without money, although money made transactions easier. Of course, you have to remember to work out how much effort and energy the items you trade are worth to you...
I have found a couple of trade goods worth considering...
A couple of years ago, I got myself a couple of coffee trees... Actually, until recently, it was two dwarf trees, two regular. Off one of the dwarf trees, I planted a bean, and found that it grew after several months. Early this season, I planted several of the beans from one of the regular trees... Well, it's taken several months, but I know have five seedlings on the go (plus one already given away), and possibly a few more to come up, although maybe not until next season.
Coffee has great potential as a trade good... A single tree will give a good crop - several trees will provide tradeable amounts, but it's not something you can easily scrump. The beans need processing before they can be used - and if your pre-trade processing includes roasting beans, someone can't use the beans to grow their own trees. What else... My Melaleuca are similar - except you extract the essential oil and sell that, so not even seeds get sold. Cotton has potential - but is a pain to harvest - once raw supplies, clothes, and rags are no longer available, although that might take a while. Dyes would be good... Pepper might be.
Basically - anything you can grow in suitable quantities, aren't readily usable if stolen.
As for what I'd want... Other foods are always good, furs, leather - anything I wouldn't have time to go and get by myself... But also books (non-fiction, primarily science, engineering), and if someone was offering a washing machine with a motor usable as a generator, I'd be jumping right on that.
I had this thought, too, that books with scripts for theatrical plays and the like might be worth effort, if a few people I know were to come up... Although that would depend on film and television not being readily available, which is a possibility.
One a plus note, a friend who is into archery has told me that, yes, he does know how to hunt, skin, and prepare game... He knows, if things go down the tubes, that he can come up here...