One-Line Rewards: Modern Magic

Although we don't usually equate modern RPG settings with magic items, there are plenty of examples.  From magical realism to myth-made-real, magical items can make a good reward in modern setting, especially if they exist as standalone relics in an otherwise nonmagical setting.

You could go the route of Warehouse 13: pick items associated with famous and exemplary individuals and give them magical properties.  Maybe Houdini had a magic wand or gloves, perhaps Jesse James had a revolver blessed by a shaman, or it could be that John Lennon's glasses allowed him to see into the spirit world.  If you go that route, I suggest picking people that died violently, mysteriously, or both, and incorporate that into the item's lore.

Or you could go another route, and pick seemingly normal, everyday objects and enchant them to suit your needs and/or wants.  That's what I've done with the list below.

One-Line Rewards

Armored Tee: A black tshirt with an image of a blue shield. The wearer is protected as though wearing a steel cuirass.

Hoodie of Illusion: An unremarkable grey hooded sweatshirt. The wearer is invisible as long as her hands are both in the front pocket.

Bus Pass to Anywhere: A blank paper ticket. The holder can board the Immaterial Express and travel anywhere in 10 minutes.

Illuminati Rifle: A gold and black ‘50s-era sniper rifle. It never misses, but anyone who fires it is destined to be killed by it.

Intelligent Phone: A clunky flip-phone with a brain logo. This phone is sentient, and communicates to its owner via text.

Swiss Army Sword: A red penknife with a white cross inside a white triangle. When the blade is opened, it becomes a steel broadsword.