Guild Wars 2

This suggestion will do three things:
– If someone tries to sell an item for too high a price (or the market shifts/price manipulation ends after placing their order, dropping the price), the price will be lowered over time so that it will eventually sell without requiring further input from the seller. Though paying attention and skilled manual intervention should produce better results.
– Remove lots of the sell orders that are 1c above the vendor price. Some will still remain, but the reduction in supply will make it easier for the items price to rise above vendor trash levels if it somehow becomes useful.
– Ensure that all sell orders will eventually be removed from the trading post. No more sell orders that remain in the trading post for years after their creator has stopped playing.

For this the trading post will need each sell order to have three new variables associated with them:
– A duration
– Reduction rate
– Cutoff value.

The duration and reduction percentage are up to ANET to decide or they could also be something players set when making the sell order. I’m thinking the cutoff should be {vendor price}/0.9. Below that, you would make more coin canceling the sell order and selling to a vendor. I’m only using the 10% sales tax in this calculation because the listing fee is a sunk cost, and can thus be ignored.

When a sell order has been up for longer than its duration, its price is reduced by the reduction percentage at no extra cost to the seller. Always round the new price down, to ensure that the price is always reduced by at least 1 copper. Then the following happens:
– If there are any buy orders greater than the cutoff, the items are used to fill the buy orders starting with the highest priced one.
– If the price is now below the cutoff value, the sell order is cancelled, the item destroyed, and the seller gets the same amount of coin as if they cancelled themselves and sold to a vendor. Maybe send them an angry mail from Black Lion Trading to let them know that, had they just vendored it, they wouldn’t have had to pay the listing fee. Which is not refunded, so it should discourage them from listing vendor trash again. If they don’t change their habits, then their bad habits become a gold sink.

If there are still items left in the order and the cutoff hasn’t been hit, then the order goes back up for the duration again at the reduced price. This will repeat until the items are sold or the cutoff is hit.

People who list items for 1 copper above the vendor price will have them removed, and the message telling them they should have vendored it, after the first price reduction.