We could've told the guy you can't get a decent invisibility spell that's arm compatible for less than 2,000 bucks.
"Magical Realms" Website
In the Fall of 2002, a would-be bank robber in Tehran, Iran decided that he needed a little supernatural help to pull off his next big heist. So he went to a "sorceror" looking for an invisibility spell, something to give him that extra edge. He paid the wizard 5 million Rials for several pieces of parchment that were supposed to be the equivalent of a "Ring of Invisibility".
Our would-be robber proceeded to tie the paper to his arms, and entered a Tehran bank. He was overjoyed at his own cleverness, and he began snatching money out of people's hands left and right. Unfortunately, it didn't come off quite as well as he expected, because his invisibility spells didn't do a thing, and everyone could see him. The bank customers quickly overpowered the unarmed "invisible" thief, and he was soon arrested.
When brought before the judge, he told his story about paying the 5 million Rial (about $625 USD), for the spell, and how he believed he was conned into his actions. He said it was all a mistake, and that a big trick was played on him. No one seems to know exactly what happened to the man after that, but this did happen in Iran, so use your imagination.
It appears the only winner in this story was the wizard, whom police were strangely unable to locate. It was like he had just vanished into thin air.