When crafting your next roguish character, think of vessels like these. Smugglers’ boats in the 18th Century didn’t usually transport goods that were illegal to consume- instead, they smuggled things like chocolate, tea, coffee and tobacco into countries with extraordinary customs taxes. Luxuries, but not forbidden.
The fascinating thing here is the creative lengths people went to when smuggling- tobacco was braided into ropes, and special barrels constructed to hide illegitimate liquids (source). Rope is easily acquired; the ingredients for plant-based potions could certainly be smuggled into a given country this way, though the smuggler might have some explaining to do when they are suddenly reluctant to actually use their twine. Perhaps coins could be hidden in chocolates, which are expensive, surely, but not as expensive as gold. Barrels would be a bit trickier to craft, but perhaps worth it to hide gnome blood or whatever item it is you need. Though, if you need gnome blood, I suggest you fill the rest of the cask with Jager. It smells the same.
In any case, props, like costumes, can make a world real; use a little smuggler’s ingenuity and see what you can make!
Théodore Gudin’s Smugglers’ Boat via Wikimedia Commons. Public Domain.
Edit: And when buying chocolate IRL, do a little research before you buy.