Coin doesn’t spawn in abundance, but there are other ways to get your money up in YAPYAP so you can buy and experiment with wands in no time.
Here’s everything you need to know about your stash in YAPYAP.
How to stash items in YAPYAP

Unlike Lethal Company and R.E.P.O. that restricts you to a three-slot inventory, YAPYAP offers a way to move items into your stash. The only downside is you cannot get these back until you extract. Outside of Coins and Wands, anything you pick up can be placed directly into the stash, where it vanishes and teleports back to the home base.
You must first pick the item up as if you’re going to equip it, leave it in your right hand, and move it into the stash from here (refer to the button display at the bottom-right corner of the screen for controller and keyboard layout). Your inventory should consists of Wands you can switch to and cast spells during puzzles, to ward off monsters, or help cause chaos to fulfil contracts. You can also carry potions that spawn inside the cauldron room (usually for healing), or carry ingredients you’ve found to then drop inside the cauldron and brew your own potion. Ingredients can be used without brewing, but there are rarer items to find and sell them on for some Coin.
YAPYAP stash location

Instead of bringing items back by hand like Lethal Company, or seeing them spawn inside the R.E.P.O. truck if you lost them mid-round; your YAPYAP stash collects in the wizard hut at the home base. Every time you move something into the stash it moves directly in the bottom level of the hut. Take the stairwell directly below the Ponder Orb to find your stash that spawns at the center of this room.
What is the stash for?

You can them pick up three of these items to fill your inventory and bring them to the merchant that speaks like the Fire Keeper in Dark Souls 3 and acts like any ordinary RPG merchant. While she looks like a boss fight waiting to happen, this NPC offers the only way to buy and sell items. Equip whatever item you wish to sell and interact with her to sell the item from your stash for Coin.