Bukkit

• You know have the option to enable the decay of the price of items over time if they are not purchased (ie, if stone isn't purchased for 24 hours, its price will decrease by 10%)

The best part is, it's completely customize-able via the new config.yml fields:

enable-over-time-price-decay: true

This will either disable or enable this feature.

over-time-price-decay-percent: 0.1

This is the percent decrease the items price will experience when not purchased for a certain time period.

over-time-price-decay-period: 1440

This is the time, in minutes, that an item must not be purchased for in order to experience a price decrease (so if stone wasn't purchased for 1440 minutes, which by the way, is 24 hours, it will experience a price decrease of whatever percent you set)

over-time-price-decay-period-check: 60

This is the time, in minutes, that DE will check if items haven't been purchased for the time you set in "decay-period". So if this is 60, DE will check every hour whether any items have not been purchased for long enough to experience a decrease in price.