I have a few things that I have accumulated over what my family and extended family will need with the idea of having for trade. I have collected quite a few butane lighters. Buying them in bulk they can be purchased for a little as 15 cents each.
Also small bottles of hand sanitizer, and larger ones which can be used to refill the smaller ones. This makes good fire starter, but the real reason for these is to stay clear of bacteria and viruses. If there is a pandemic these will be worth an astronomical amount as will face masks and respirators.
Somehow I have ended up with more antibiotics than I probably would ever need for my family. I have a bit that can be used for trading if the need arises.
I have an accumulation of the small jars of coffee useful for trading. Sure I can drink it now, its not bad, but I save money by purchasing in larger jar for myself. I buy the smaller jars on sale for a buck or two and they are good trading size.
Alcohol I have various kinds. I do not drink alcohol a lot, but what I like I have stocked. If SHTF I can trade any I want. But specifically for trading I have smaller bottles of vodka and whiskey.
I also have a jar of a couple hundred cheep folding knives. They are nothing special, but might be handy. Now I sometimes give them away to friends or kids. In SHTF they may be used to sweeten a deal or for someone who does not even have a knife.
Ammo – One thing I have learned from SELCO in light of ammo and guns is to be careful who you trade this to so it is not used against you. However, even under current ammo situation in USA I have used my ammo to help friends out. It always has worked out week for me as well (in the long run), and friends are the ones who will help you so you want them to have ammo and firearms.
Seasoning & spices – I have salt and pepper as well as other seasonings. In the old days one of the reason for the trade with the orient was to get herbs and spices. A big reason for this was that there was no refrigeration and spices helped to make marginal meat palatable. It also helps make wild game taste great, and helps those who are not used to the taste of game much more easy to accept.