Issue
Currently a lot of items aren't sold on the TP soley because they pass the max cash limit (2147m). This is the twisted bow, scythe of vitur, a few nightmare items (inquisitor, staves/orbs), elysian spirit shield. This makes it so finding a player who's selling may make it a bit more difficult, and creates a type of monopoly if you're the only player online that is selling the item at the time which can create a price gouge if the other player wants/needs the item quickly.
Suggestion
Allow players to pass the max cash limit on the TP by having it take into account platinum tokens. If a player lists an Elysian spirit shield for 5b, then have the player need a total sum of 5b between coins and platinum tokens to purchase it.
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Pros
Would move items easier in the eco that you currently have to find a player to buy off of.
Cons
Not sure, I'd say less player-player interaction, but don't see how that's an issue considering every other item can be bought off the TP.