In episode 6 of the first season of Durarara!!, we see that Kadota is gainfully employed doing some sort of construction-related manual labor.
But his three buddies in the
Mystery Machine Dollars van don't appear to do anything that would earn them a dime - they just drive around town doing god-knows-what. Karisawa and Yumasaki seem to spend stupid amounts of money buying light novels and merchandise and stuff; and I'm guessing it costs Togusa a pretty penny to fund his Hijiribe Ruri habit.
How do the three of them afford anything?