The Auction House is a facility that allows Heroes, Villains and Praetorians to buy and sell Enhancements, Recipes, Salvage, and Inspirations. The Auction House works across servers. Items being sold from any server may be purchased on any other server. Trading now exists between all factions: Heroes, Villains, and Praetorians. Prior to Issue 18 trading between different factions was not allowed.
A character may begin using the Auction House from level 1. This allows the buying and selling of items in the event the character's personal and vault storage becomes crowded. The /ah slash command can be used to access the Auction House from almost any location.
There are physical Auction Houses in-game: Wentworth's Fine Consignments, located in Atlas Park, Kings Row, Steel Canyon, and Talos Island; the Black Market, located in Mercy Island, Port Oakes, Cap au Diable, Sharkhead Isle, and St. Martial; and the Trading House in Imperial City or the Underground Trader located in the Resistance Hub of Underground Imperial. The slash command means these serve little purpose other than for Day Job badges.
At level 10, a contact becomes available that provides a training session similar to a story arc, to introduce the Invention system. Players may wish to wait until level 12, as the reward for the arc is an IO (level 12 allows the choice of a usable level 15 reward).
Secret Bid System
The Auction House uses a secret bid system. Here is the in-game explanation of this system as provided by the Wentworth's Employee in Talos:
- At Wentworth's we use a 'secret bid' auction. To make a long story short, you set the price for your item, but the Buyer does not see it. The Buyer bids what he wishes to pay and if he meets, or exceeds, your requested price he will receive the item. You may even receive more than you asked for! In order to help the Buyer with a bid, there is a history of how much that item has sold for in the past.
If multiple players are selling an item for different amounts, the person with the lowest list price will sell first as long as a bid is higher than their list price. Thus, if a lot of people are listing an item for 100 inf, someone who lists the same item for 10,000 inf may never sell it even if people are paying 100,000 inf for it. Likewise, it's possible for someone who lists an item for 100 inf to sell it for 100,000 inf while someone else who lists the item for 10,000 inf only sells it for 10,000 inf.
If two offers are for exactly the same amount, the offer placed first will usually be resolved first. 
Each character has a limited number of transaction slots that they may use at the Auction House. A character starts with 45 and earns more as they advance in security/threat level (see the Leveling Chart for details). Additional transaction slots may also be earned through badges.
One transaction slot is required for each item put up for sale or for each bid placed. Salvage and recipes may be bought or sold in stacks of up to ten. Enhancements may be bought in stacks of ten but can only be sold singly.
Fixed Price Items
The vast majority of items available in the Auction House are sold by players. However, some items are stocked by the game.
An infinite supply of invention salvage is available at 10,000 inf for Common Salvage, 100,000 for Uncommon, and 1,000,000 for Rare.
There is also a one-use market teleporter, available either as a Consignment House Transporter (for heroes); a Black Market Transporter (for villains); a Trading House Transporter (for Praetorians); and a Underground Transporter (for Resistance). The Market Teleporter may be purchased at a fixed price of 10,000.
There are two sets of fees associated with using the Auction House. Both fees are applied to the seller, a listing fee and a transaction fee.
Because there are fees associated with selling on the Auction House, it is possible to lose money, especially when items do not sell.
Notice, though, that you are essentially only charged one fee, since the second fee is never charged if an item doesn't sell, and if it does sell, the first fee is deducted from the second. If you put an item up for sale and it gets bought, your overall net profit is 90% of what the buyer paid for it, no matter what minimum price you asked for. (This is technically untrue at the extremely cheap end, where items are priced so low that they sell for less than 50 influence, but the extra charges in these cases are in the low single digits.)
When an item is put up for auction, a fee of 5% of its listed price is charged to the seller. If you do not have enough influence/infamy to cover the fee, you will not be able to list it on the Auction House.
Note that the minimum fee is 5 inf. If 5% of the list price is less than 5, you will still pay 5.
If your item sells, this amount will be refunded. The amount will not be refunded if the item does not sell, or if you cancel the auction.
When an item sells, a transaction fee of 10% is deducted from the amount it sold for. However, the transaction fee will be reduced by the listing fee, which will be refunded since the item sold.
Inventories, bids and items for sale remain in the Auction House indefinitely until claimed or acted on, even if the account is inactive for a long time.
- Main article: Influence Transfer
Influence can now be transferred to characters on your account, or to other players, using in-game email. This is the only recommended way to transfer Influence. Before this feature was available, it was sometimes done more clumsily via the Auction House.
You've sold 50 Inspirations on the Auction House.
You've sold 50 salvage on the Auction House.
You've sold 50 Enhancements on the Auction House.
You've sold 10 items on the Auction House.
You've sold 50 items on the Auction House.
You've sold 100 items on the Auction House.
You've sold 250 items on the Auction House.
You've sold 500 items on the Auction House.
You've sold 1000 items on the Auction House.
You've sold 2000 items on the Auction House.
You've sold 3000 items on the Auction House.
You've sold 4000 items on the Auction House.
You've sold 5000 items on the Auction House.
You've sold 5000 items on the Auction House.
You've sold 6000 items on the Auction House.
You've sold 7000 items on the Auction House.
- Number Six, Discord, 13th Sept 2021