This is the perfect mod, that would fit into variable and conditionable events.
You know that City RP mod, well, it would display your cash at the bottom, and events would do the rest.
Shop:
OnActivate>Player>TakeMoney>100
VariableTrue>Player>AddItem>Sword
Quest: (My main focus)
OnActivate>Client>CenterPrint>Bring me wood!
OnActivate>Self>IfItemInSlot>Wood
VariableTrue>Player>GiveMoney>100
VariableTrue>Player>RemoveItem>Wood
VariableTrue>Client>CenterPrint>Thanks!
In my <Secret Project Here>, I just use keys as currency that you turn in for items. This is simple, and good.
TakeMoney would be a true variable IF someone had and gave the money.