I have to disagree with your list. Everything on it is something you might need and not be able to replace. Sure its makes sense that people would want those items, but wouldn't it be better to trade luxury items, or items that are cheap now, but hard to get in a disaster?

How about soap? Soap lasts forever and its relatively cheap. In a disaster hygiene is both a luxury and an absolute necessity to combat disease. While you can make soap pretty easiy from animal fat and wood ashes, how many people will actually be doing that (or have animal fat to spare)? Soap is potentially a very useful item for trade.

Salt is another item I'd consider, it has many, many uses. Its hard to obtain in most places of the world unless you live on the coast or near a large halite deposit. But again, during normal times its cheap and easy to store. I'd get coarse Kosher salt by the 3 lb box and put each box in a zip lock bag (only important if you live in a really humid climate). Already measured out for easy use and trade.

Finally, what about unroasted coffee beans? More expensive then the other two, but if you can trade a luxury item for a necessity isn't that better then trading necessity you might need later? For people who drink coffee changing your drinking habits a bit would make stock piling a supply to trade laughably simple. How many people do you know that are ready to kill for a cup of coffee after only a day with out caffeine?

Finally, I would strongly oppose including firearms more then anything else on your list, simply because I dislike the possibility of arming a potential enemy. Besides firearms are expensive, I can't store nearly as many as I can other items, and they're only good for big purchases. However, I might give a firearm to someone who was my ally or to cement a treaty. Selling a firearm gives away a tactical advantage, while giving it to an ally creates a more solid tactical advantage.