Some idea's to dump A LOT of gold.
- Add a NPC at home that sells bonds for a price of 80.000.000 coins. This might be a bad idea in a few of your eyes, but it's a hardcore way to dump a lot of gold. A month or two, having it sit there will have dumped a lot of money. Hold track on how much has been removed from economy!
- The imbue of items (rings, slayer helms, ...). This could be done by the slayer master for a price of 15.000.000 for a ring and 25.000.000 for the helmet. Yes the voting way is cheaper, but can only be done once a day. This won't affect the economy and is a clean money sink.
- The rare shop. This shop can be placed at duel arena and would sell following items. Partyhats, h'ween masks, santa hat. This for a price range of 450-999m.