Every MMORPG has an Auction House or some variation of a common venue that allows players to trade items and resources among themselves. The Auction House in World of Warcraft is the pulse of every realm and reflects what's most important to the players, and sometimes the most expensive items aren't optional. No matter how much a character tries to save their precious gold, there are things they're compelled to buy.
Sometimes it's a question of gear, with certain Best-in-Slot (BiS) items that are only available if a player either makes them, picks them up, or buys them. Those interested in specific Achievements or completing their personal collections might also be willing to pay for that one missing item instead of farming for it. There are plenty of items in World of Warcraft that cost a ridiculous amount of gold, and saving up enough to buy that essential item grind.
7 Siren's Tear
Sockets, and the gems to fill them, was a new concept in The Burning Crusade expansion. The idea was kicked up a few notches in The Wrath of the Lich King. and one of the most coveted gems that players farm or purchase is the Siren's Tear. It's not just used in Jewelcrafting, but also in Tailoring for BiS items like the Wispcloak and Deathchill Cloak.
There are few places to find it, which is what drives up the price. It's usually the fisherfolk that have them because they're a rare drop from Darkwater Clams and Wintertfind Clams. Even uncut, the gem sells for more than 100g on the Auction House, and players often need two or three to finish certain recipes or fill a few sockets.
6 Recipe: Greater Arcane Elixir
There are a few high-level recipes that are consistently expensive, and this is one of them. They might drop from rare spawns or appear as loot in dungeons, and demand is high for them, so the guild's alchemists can make the essential consumes for raid times.​​​​​​​ The recipe for the Greater Arcane Elixir drops in a variety of high-level dungeons but is a rare item that's also BoE, so anyone can pick it up and sell it.
The recipe for the Greater Arcane Elixir has existed since Classic and the buffs that it gives, which include +35 to spell power and +10 to critical strike rating, give the spellcasting classes an insane damage buff. That's why players consider themselves lucky if they see it on the Auction House for less than 150g.
5 Glowing Pebble
Pebble the Penguin is a non-combat pet that only exists in the present version of WoW: Classic and wasn't in the vintage game. It's only available to players who purchased the Northrend Heroic Upgrade​​​​​​​ or the Northrend Epic Upgrade from Blizzard, and a package that included various goodies, like extra gear, a fishing buddy, and Pebble the Penguin.
The Glowing Pebble is one of many rare gifts players can get from Pebble if they happen to have something in their bags the penguin wants to eat. Collect enough and get rewarded with an Achievement, which is the main reason this non-soulbound object sells for around 9,000g.
4 Mechano-hog
Unlike other unique mounts that were introduced in Wrath of the Lich King, like the Magnificent Flying Carpet or the various mammoth mounts, the Mechano-hog is a Bind-on-Equip (BoE) item and players don't need to be Engineers to use one.
Players do have to be Engineers to make one, however, and the materials are uncommon and expensive. Collecting them and paying a professional to build one might be slightly cheaper, but for those that are collecting mounts or are dedicated gearheads, they cost about 15,000g on the Auction House.
3 Darkmoon Card: Greatness
Some trinkets are only good for specific classes or quests, but the Darkmoon Card: Greatness is great for virtually everyone along with being the BiS item for several classes. Every time the holder does healing or damage, their Strength, Agility, Intellect, or Spirit has a chance to gain a buff of 300 for 15 seconds. The character's highest stat is the one that's automatically chosen,
It used to be that the only way to get this trinket is to bring a completed Nobles Deck to Professor Thaddeus Paleo at the fair, but Inscription has made it possible to make them and sell them on the Auction House. That hasn't brought down the price, which hovers at about 40,000g on the Auction House.
2 Arcanic Tramplers
The Arcanic Tramplers are the BiS for all of the heavy DPS hitters, like Warlocks and Mages, and only drops from Malygos, the big boss of the 25-player version of the Eye of Eternity raid. Purple BoE items are always expensive because there aren't that many of them, and these boots are currently one of the most sought-after and expensive in the game. ​​​​​​​
When one drops in a raid or dungeon, there's often a quick debate to be had about the rolls to ensure every player is in agreement before the item is doled out. ​​​​​​​If there aren't any players that need them which is unlikely in the first place, it's awarded using other means and if they don't go to an alt, they end up at the Auction House. If they're for sale for anything less than 18,000g, it's a steal.
1 Je'Tze's Bell
There are all kinds of jokes about the name of this bell, but it's no joke that this trinket is a BiS for several classes and a purple BoE drop, and when it comes to sale price that's no laughing matter. It increases the wearer's spell power by 106 and has a chance to return 125 mana for 15 seconds, which is great for any spellcasting class.
Like other rare and expensive purple items, Je'Tze's Bell drops from a variety of elite enemies in heroic dungeons, but it has the best chance to drop from the Archavon Warder, which is a boss from the Vault of Archavon. The Vault of Archavon is only accessible if the player's faction controls the fortress in Wintergrasp, which limits the availability of this trinket even further. Save up at least 4,000g before seeing if the AH has any for sale.
World of Warcraft is available on PC