Crowbux
Crowbux are ornate golden coins are the ceremonial currency used by The Crows.
Individual coins significantly larger and heavier than standard gold piece coins. Each crow buck is worth about 5gp in gold by weight. They bear an iconic crow and skull motif that is instantly recognizable by those familiar with the guild. They have no denomination, writing or symbols so they can be passed off as foreign coins with a good enough bluff check. Most vendors and guards do not recognize their significance.
The coins are accepted by a network of vendors and service providers throughout all the areas where The Crows do their business. Paying in Crowbux gives one access to private safe houses, skilled weapon and trap makers, alchemists capable of crafting deadly poisons and more. The Crows maintain this secretive and bustling black market to provide support for their operatives.
"Shaved" Crowbux and Crowbuck halves and quarters, or hole punched Crowbux frequently find their way into regular circulation. This is done on purpose to provide plausible deniability to anyone captured why carrying the coins.