A few tips for farming Psitanium during and after you beat the game.
How to Unlock The Astral Wallet and Farm Psitanium
Unlocking The Astral Wallet
Upgrade your wallet to the Astral Wallet as soon as you can. Each upgrade (2 in total) are sold in the Otto-Matic.
Once you have the astral wallet unlocked, save your Psitanium until you reach 5000/5000. It is much easier to save up this much during the game’s main events, and it becomes much harder to earn Psitanium once you finish the game.
Useful Items and How to Use Them
As soon as you can, collect all the supply chest Keys and Unlock all supply Chests (Note that some chests and keys are not available until after you unlock all the powers). Some chests give 200+ Psitanium when opened.
At rank 8, buy the Mental Magnet pin and equip it. Begin collecting every Psitanium deposit you come across. The questionable area is a good place to roam around and farm deposits. You can do this without the pin, but collecting the deposits is a bit annoying without it.
At rank 40, buy the Mental Tax pin and equip it. There is a (pretty high) probability for each mental connection node you pass through to drop 10 Psitanium and you can trigger the same node more than once by traveling across it again. If you get to the end-game and need to farm Psitanium quickly find a suitably long chain of mental connections and simply travel back and forth along the connections as fast as possible.There is a chain of stray thoughts in the QA near the playground that can be used.
At rank 50, buy the VIP Discount pin in order to decrease the price of all items in the Otto-Matic. This will help you buy all the items. Note that you only need to wear this pin when you are buying items, and it can be swapped out for another pin when you are done shopping.
At rank 52, buy the Psimultanium pin and equip it. This pin doubles the drop rate of all Psitanium.
Note that you cannot pick up nuggets that would over-fill your wallet. If you get stuck in a situation where you can’t find nuggets small enough to get exactly 5000/5000, try burning small objects. They often drop very small amounts of Psitanium.