So what sort of grifts exist in a world with magic?
Well, the most common, of course, if there’s any sort of short-term transmutation magic, is the Fairy Gold Gambit, where you transform a worthless item into something that seems valuable only to have it wear off after you’ve taken payment and skipped town. The risk here is whether the mark has a way to test things before you’ve gotten away. (Actual fairy gold’s probably gone out of style since if you touch it to iron it changes back- but it’s a venerable enough tradition that it gave the practice its name.)
The Red Shoes Scam, also know as the Cursebreaking racket, has some elements of the Fairy Gold scam- except here, the item is worthless because it’s dangerous- the most famous example being a pair of red shoes that causes whoever to wears them to dance themselves to death. Once you’ve gotten the mark to bite on the cursed object (Ideally, in a way where they -can’t- go to the authorities- perhaps your accomplice presented it to them as stolen goods) you turn up and offer curse-breaking services, for more money than they paid for the item in the first place. This one’s a favorite because it involves multiple payouts.
The Haunting con: Ghosts have wants and needs- wants and needs that are most easily provided for by spiritualist or necromantic mages. Not all necromancers are interested in the whole ‘armies of undead servants’ thing, either. Some are just interested in money. When a necromancer works together with a ghost, they can set up a highly efficient protection racket where the ghost haunts a target till they hire the necromancer to exorcise them. Some combine this con with training the ghost to case the house for valuables and security, and work with a second-story guy to clean the place out on top of the con.
The Ancient Secrets ploy: Magic is hard to learn and hard to use. But not everyone’s willing to believe that, which is why you can sell them sure-fire methods to learn and use spells easily. There’s several variants on this, ranging from the just embarrassing correspondence course scam where they pay you for lessons that never work to the actually dangerous dealing in limited-charge magical items that are designed to run out of uses just in time for the next round of payment.
The “No, it’s literally a badger” game: The regular badger game is a term for having an attractive young woman seduce a married man into a compromising position, suitable for blackmail. This magical variant is about convincing a would-be magician that he’s made a profound mystical connection to a familiar creature that’s actually under your control. It acts sick, requiring expensive medicines that you supply, needs special feed since obviously it’s a magical creature, and so on.
The Faust Game: A bit of a combination of both the last two scams, you sell someone a means of summoning a demon- a demon under your control- while leaving out important details that get the wanna-be diabolist into trouble, whereupon you appear as a guardian angel and wring concessions out of him, with the demon playing the soul-devouring bad cop to your good cop.