How about instead of not allowing people to ever purchase the same item or type of item ever again, you put a massive "cooldown" on buying the same item again (like 1-2 years maybe). One is already not allowed to purchase more than one item per month. It would make sense for the same item(s) to perhaps have an extremely long duration in which you cannot buy this item again to prevent people from "cornering" the market on that item.

This way certain items are not left up for sale for an eternity because hardly anyone else remaining has enough fg + is qualified to buy it. Also would help stabilize prices somewhat in these forums and can only benefit sellers in terms of the demand for their item.

Just a suggestion, I can understand if there is some other extenuating circumstance for why the policy is how it is currently. Also do not know if this has been suggested before. Please don't flame