The Misplacer Beast

An elven woman named Nikym, who deals in stolen goods, who operates solo as a business. Usually her goods are, as she insists, "misplaced" objects. If needled on origin she's only ever willing to come up with grand stories about how she acquired items and doesn't even try to lie particularly well, but she is still careful to never up and say the goods are stolen. Her shop is behind a magic door that can be summoned wherever a specific cat eye drawn in a particular chalk is found. One need only stand by this door and say they could "stand to misplace a little more." Her beloved pet displacer beasts, Shazi and Ra (two females,) are always within the main shop area- often to either side of the door since their favorite pillows are there.
If someone buys anything from her in a manner that she would like to encourage or exploit a second time, or if someone proves to be a particularly good source for rare items, she will give them a special piece of chalk that they can use to draw the same eye on any stone material wall in an alleyway provided it is a space where teleportation is allowed. Her confidence in this method of entry not being abused is credit to how dangerous she likely is to fuck around with.
The true extent of her power is unknown and she seems to like it that way. It is possible she might not even be remotely combat capable herself. Her business seems to have touch-and-go relations with more localized crime syndicates whom she often collaborates with, but despite paying well she's also exceptionally good at taking the most worthwhile jobs out from under their noses via freelancers. She has a nasty habit of making herself too valuable to chase off, but only just.
The Misplacer Beast deals exclusively in high-end items. Difficult to create potions, high level spell scrolls, precious stones, diamonds and other expensive consumable components, and interesting magical items. Her advertised stock is always rotating but her most expensive goods don't move quickly.

"If I don't have it, I probably know how to see it misplaced. I can even get you casting and crafting components of... organic nature that require discretion."

-Nikym, who is being not creepy at all

The availability of such items is balanced by the absurdity of their pricing. Nikym charges a lot for the rarity of her items and the convenience of accessing her location from anywhere, as well as for the risks she takes. 200% mark ups from expected market price (if such a thing even exists for the item) and more are very common. She knows someone will pay it out of desperation or when convenience talks louder than savings. She isn't shy about the fact that she asks for very lofty payment and is not a fan of haggling or discount seeking.
Casters desperate for certain materials and parties sorely in need of certain medicines or solutions are her typical clientele. She isn't against catering to a rich collector but can typically smell money. If someone swaggers in with too much confidence in the depth of their pockets she's almost certain to ask for more.
Here is an example of advertised goods to first time customers:

Magical items:

• Ioun Stone of Protection, 3,600 GP
• Wand of Secrets, 4,500 GP
• Leather Armor of Resistance to Cold, 16,600 GP
• Marble Elephant, 18k GP
• Brass Horn of Valhalla, 25,200 GP
• Robe of Eyes, 90K GP
• Ioun Stone of Greater Absorption, 124k GP
• Scarab of Protection, 144K GP

Diamonds:

• 8 worth 25 GP, being sold for 50 GP
• 5 worth 300 GP, being sold for 500 GP
• 2 worth 500 GP, being sold for 1200GP
• 1 worth 1K, being sold for 4K GP
• 1 worth 10K, being sold for 50K GP
• X10 Diamond Dust worth 100 GP being sold for 250 GP

Advertises availability of: Adamantine, Rubies, Agates, Sapphires, Gem Chalks and Inks, Fine Incense, Gold Dust and some Dazzling Gem Goods such as eatery and jewelry chests

Potions:

• X5 Potions of Greater Healing: 525 GP each
• X1 Potion of Gaseous Form, 900 GP
• X3 Potions of Superior Healing: 1,580 GP each
• X1 Potion of Supreme Healing: 4,050 GP
• 3x Potions of Invulnerability, at 11,600 GP each

Scrolls at 92,200 GP each:

• Scroll of Storm of Vengeance
• Scroll of Mass Heal

Scrolls, all 123k GP each:

• Scroll of Time Stop
• Scroll of Astral Projection

Scroll of True Resurrection, 676k GP

I can always see it conveniently misplaced.