This is a prolongation of a previous question about the culture and traditions of "invisible" people.
This world is close to ours, except supernatural creatures exist and have formed their own well-organized and extremely discreet mafias. Most creatures described in legends from around the world can be included in the story.
As long as it's possible for them to remain more or less hidden they exist, so no giant fire-breathing dragons. They can be little more than humans with powers (ex: warlocks, oracles, mediums), human-like creatures (ex: djinns, wendigos, vampires), non-humans (ex: kistune, talking snakes, swamp monsters) or ever shapeless creatures (ex: poltergeists, forest spirits)
Some of them can make objects with a spell attached to that prevent normal people from paying attention to or remembering them. For example, a necromancer could leave a collection of ancient grimoires in the middle of a kindergarten, no one will ever question their presence and no toddler will use them as coloring books.
The objects in question can be almost anything : books, clothes, trunks, blankets, flasks... The only condition is that the object must be made of or entirely covered by leather and/or bone.
In this setting, members of these mafias use leather bags to move stuff across the world. For example, they can export human blood and organs and sell them to vampires and other various cannibalistic creatures.
No matter what's inside the bag, the border control won't pay any attention to it, no matter the sounds or smells coming from inside of it. However, the number of magical bags is limited to a few dozens.
My question :
In the real world, the most smuggled goods are people, drugs, weapons, exotic animals, minerals and money. And like real world mafia, the supernatural families thirst for money, power and social status (inside of their circle).
What is the most efficient way for them to make use of these bags?