Answer:
The most fabulous way to locate pots of gold
Sitting down you have it, Standing up you don't.
The buyer doesn’t want it, the producer doesn’t need it and the user doesn’t know their using it.
What is the middle of water but is not an island?
There's one in every deck of cards and in a famous movie
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.