Transference Monks

Very few people pay attention to the tall, red-robed creatures that trundle through cities and stations, speaking to no one, stopping nowhere, and eating nothing. They are scrupulously law-abiding, but they carry no documents. They walk like elongated humanoids, and they clearly have arms, but their robes and wrappings cover everything except a tiny metal eye-plate.

Transference monks are one of the wonders of the galaxy. They are very rare. They appear, linger for years, and then disappear.  

Toshdor Ni by Phraggle

If you know their language, you can make yourself a metal plaque with strange jagged lines on it. Present the plaque to a Transference Monk, speak a few words of their language (it sounds like trying to unclog your ear with an electric drill, but quieter), and then hand them money.

The Monk will accept the money and vanish.

At any point, if you ever meet another Transference Monk, you can present your plate again, speak some other words, and ask for any amount of money back. The Monk will wander off and, within a few hours, find you and give you your money back. And it is your money - you can check the fingerprints, if you want to. Nobody knows how they do this.

If you read their mind with the Force, you'll find there isn't one. If you try and disrobe one, they'll break your arm casually, from the shoulder to the fingertips, like squeezing a tube of toothpaste.

Shoot one, and they die, then burst into bright white flames that leave only ash behind. Capture one and after a few hours they immolate, this time explosively.  Scholars speculate that they are natural Hyperspace users, or possibly relics of some long-dead civilization, but nobody really knows.

If you die, your coins stay with the Monks. If you present a body (at least 80% of it, including wherever the thinking bits go), and a carved metal plaque, you can potentially collect the coins the dead man deposited. The Monks might also ignore you.

Learning of the existence of the Transference Monks is valuable. Learning how to use them has made many smugglers rich. It's a secret worth killing for.

Learning the location of Rexalos Vidlar's tomb and his metal plaque is worth invading a system for. Rexalos' vast wealth was never found. His palace was completely empty, his coffers contained nothing but traps and droid-assassins. He was so wealthy that even a thousand thieves splitting his wealth a thousand ways would have been too rich to disguise. It must have gone somewhere, right?