Caravans in the wasteland will usually be carrying produce or supplies such as scavenged plastic, scrap metal, wood, barley, cattle, and more. All of these are vital to a raider operation -- but occasionally, you may receive intelligence of a treasure convoy carrying an ancient artifact from one settlement to the next.
Sure, televisions sets and old cars are also considered ancient artifacts... but these are truly ancient. Old items plundered (or saved) from the world's museums before the great catastrophes, items such as the Euphonious Krater, the Canopic Jars, and the Pharaoh Death Mask for example... items that will provide valuable insight into the past cultures and civilizations of our planet if reconstruction and recovery ever takes place.
Naturally though, you're of the mind that these priceless artifacts would look better in your own collection...
Treasures not only tie your treasure room together, but also provide organizational bonuses as well. Incredibly rare in the wasteland, it's a big deal if you are able loot an artifact of importance.
Casino Chips
The main tendered currency of the wasteland was deemed to be casino chips.
People considered other items, bottle caps for instance - but casino chips were deemed more practical in the long run. Small, colorful, plastic objects with numbers on them... it sort of made sense. So now, people fight and die over them.
Of course, there are many ways of obtaining chips in the wasteland if you're an unsavory fellow: for example, you can attack people for them, you can trade produce for them (stolen, looted, or generated from captured industry), you can exchange captured hostages for them, or you can counterfeit them (if you have built a plastic mold in your hideout).
Your raiders depend on a steady supply of chips streaming in - feed their greed or watch their morale start to drop...