If we can use ingredients not yet available, what will they be, how are the acquired and how rare.
Gems- mined, won , stolen - there are many suggestions on gem stones
Eye of newt - mission - easy but time consuming - must re-run mission each time - something like an actual fleet must take x number of crew to a specific port. They hunt in that port for Newts. Best ports change and should be noted somewhere. Maybe in the Tavern
Mermaid Tears - must go fishing in specific- global events posts weekly what port mermaids have been spotted in. must get x amount of fish from that port and you are awarded mermaid tears.
Kraken scales - if someone attacks you with a kraken you are awared 1 kraken scale.
Tooth of leviathan - if someone attacks you with a leviathan you are awarded 1 leviathan tooth.
Daughter - must be at 100 affinity and walking on clouds - then you can sacrifice her - once she is used you must win her back again
Ship - must be a specific type of ship with a certain att level - something very specific say a 42 att regular merchantman -
I would say you could potentially open an ingredient exchange as well.
These are just a few examples - I am open to suggestions for more