Need help with merchant npcs

I’m in the process of trying to come up with inventory for my merchant npcs. They’re all pretty early game (level 3) and this is their first major location. I know the standard bag of holding and health potions, but I also want additional ideas that also might cater to their characters without making them too overpowered. The party consists of a berserker barbarian, abjurer wizard, battlemaster fighter, and a circle of the sea Druid. We’re also playing 5.5e, I don’t know if that matters or not. I’m not opposed to miscellaneous items that might have niches uses.