Strictly Profitable

 refers to an unmarked and repeatable quest in Fallout 3.

After completing Strictly Business Grouse in Paradise Falls pays you for every slave you bring him. He also provides you with the necessary equipment (Slave Collars, Mesmetron power cells). The Mesmetron power cells cost a rather steep price at 200 for 10; but with enslaving one person you gain 250 Caps, making around 230 caps - so this is rather easily fixed.