You might want to consider using a normal AW barter system as the base and then some other moves to handle the outliers of wealth.  For example:

Perhaps a character who you want to be constantly poor either has a move that lets them spend barter for some effect to keep the money flowing away from them, or has custom gigs (like the Operator) where the benefit is in intangibles (like clues, +forward, insight, or whatever) and the catastrophe is -barter or debt collectors catching up with them or something else that makes money flow away from them.

And perhaps a rich dilettante only has a normal amount of barter, but has a move to get goods and services without paying barter for them. Similar to the Chopper telling his gang to turn out their pockets, or perhaps even the ability to use the standard barter moves but with +hot instead of +barter spent.  Call the move "Well Connected Trust Fund" or the like.