The Money Wrench can be purchased during the final stages of the game. In my experience, as soon as you see the sink show up when you're questing for the musical notes, interact with it to learn about the clogged drain. Once you've been told about the sink's history, go over to the right side of the Tower of Time HQ and you'll be able to interact with the Money Wrench by the entrance in the background. Make sure you've purchased all your upgrades before buy the wrench because The Artificer will sell it to you at a convenient price of all your available time shards.
You'll see the wrench right by The Messenger's head in this picture.
Once you have the Money Wrench you'll need to interact with the sink again and finally unclog the drain, but breaking the wrench in the process. Interact with the sink again to travel to The Craftman's Corner where The Iron Hood has a shop.