Best bartering value to NPCs

[Siiepher]

Hello, I currently don't have any professions, so I'm wondering what is the highest value per material item that I can make to trade the NPC vendors for.

[Esteban W.]

There are so many different items that make you some decent cash, it'd take a while to list them all. If you're talking crafting, Combat shotguns go for around 1.5k if they're quality-Unique.
Most traders buy them, and they're pretty easy to make. If you're going to lockbox around, generally everything you find can be sold for a decent price to most traders. The Tobacco farm is fun to farm, I've heard that if you grab as much as you can carry and head out to multiple traders, you can make some serious dosh. Other than that, I really don't know.

[3.14]

For vendors that don't want shotguns -rockets, 14mm ammo, plasma pistols,  metal armor mk2. XL will also get you a lot  of caps.