quick buck
Money made quickly and/or without effort, often through dishonest, unscrupulous, or ethically dubious means. Often used in the phrase "make/earn a quick buck." The people hawking T-shirts commemorating the tragedy are just looking to make a quick buck.
quick buck
and fast buck n. a quickly or easily earned profit. I want some kind of scam where I can make a quick buck. I’m always on the lookout to make a fast buck.