Nick paid Screed $100 for information.
In Blind Faith, Nick Knight goes to Screed for information about carouche activity in the Toronto region—in particular, whether he knows of anyone who might have accidentally brought across a dog. Screed makes it clear that he wants payment for cooperation; and Nick hands over a $100 bill to him. In this transaction, Screed is clearly behaving like any underworld police informant; and Nick treats him as such. Once paid, Screed does indicate that there is at least one carouche other than himself living in the area.
The Canadian $100 bill is printed with brown ink. Canadian banknotes in other denominations are printed in different colours.