Multiverse uses AllPay. This allows us to support a bunch of different economy plugins as well as items. Please check the AllPay Wiki
To set the price to enter a world, simply go to that world and type
/mvm set price X where x is the amount to enter.
Cool, we want you to too! Simply type:
/mvm set currency ITEMID where ITEMID is a Minecraft item ID. You can find a list of them here.
Don't forget to set the price!
/mvm set price 5 FernWorld
/mvm set currency 3 FernWorld
It's really that easy.