The Brief: Bands are cash money.
One band is usually $1,000 in cash, referring to the currency strap or rubber band that goes around a stack of $1,000. Blue bands are stacks of $10,000, as new $100 bills have blue ribbons sewn into them, and would likely be stacked in groups of 100.
Blue bands, blue bands, get my cash from drive-thru –Travis Scott, “Carousel”
Other names for bands include bandz, rubber bands, and stacks.