[@Buuy]
#IF
check [123] 0
checkgold 1000000000
#ACT
Take gold 1000000000
Give QuestItem(S)
set [123] 1
#SAY
checks flag number 123 has not been used, check has enough gold, takes gold, gives item, sets flag to used.
you'll have to make sue the flag number is already not being used for...