I think that it's a good idea but needs refinement: Folks would just move their items to cheap RS gold be at the top end of that 10%, there by pushing the average GE price, rinse and repeat and the cost of the thing on that day will likely bloat very aggressively. If issue 1 exists, than wealthy players wait patiently to sell on the day and will stock pile items, as it is an payout and the price can be manipulated. I believe there has to be a lockdown before it, on the price of this item of the afternoon.

Possibly a different mechanic may be used, such as the item of the day is worth 1.1X it has average GE worth in gold should you drop it straight in the pit. In that instance it's 10% less expensive on average to throw the items in to your pet. I assume this could be abused the in the exact ways I listed above but just a thought. Could also tackle it by not. There is zero reason for us knowing it other than to abuse it do not tell us. I'm sure some folks might figure it out, but they'd be guessing, and they might also change up the item to 2-3 objects rotating throughout the day or any variety of solutions to address individuals abusing it.

I meant like when a product is chosen we would know almost immediately, not ahead (you could try to predict beforehand but that might not be accurate like you said). How I read OP's design there will be a number of the'item' after it is chosen removed from the market. So this spike in thing sells and/or associated shift from the supply/demand curve would be an instantaneous alarm bell. Any marginally effectively trained algorithm would be able to decide on these sink things up (presuming they were really having an influence on the market, which if they are not, then what is the point). With the method I am describing it wouldn't be something that you could call ahead of time but it would be something after it happened that you would know pretty quick.

More broadly, I'm just pointing out that its really hard to'conceal' an artificial restriction (at least one which produces a significant effect ) on a marketplace if there's sufficient data readily available on the market. Product prices and demand curves are quite revealing on things like that. There could be workarounds, by having a list of things instead of one that are randomly chosen or intentionally jumped around such as obfuscating. If implemented word for word However, it could definitely be a problem for the design of OP.

Make it an occurance that happens at the end of the ditch. The correlating GE sales of the arbitrary unknown thing are bought out if 10billion is chucked then. No notification of it happening. No chance for abuse. Yeah thats not a bad thought. To minimize abuse potential even farther I would also suggest making the buyouts occur at random intervals, to prevent people from only stockpiling random items and then posting them at 9.9% over market place right before the buyout happens. So if the buyouts are random its still possible to do that, but you would be sacrificing all of your GE slots to buy 2007 runescape gold get things sitting there all of the time so it would be a bet.