I'm sorry if this is not the right place, but I couldn't find a better one.
My suggestion is that players were allowed for voting for what would be the next sale, like on wednesday, and on thursday it would be published the most voted.
This should happen one time per month and the discount should be suggested by the game-master.
obs: Sorry for my english, but I thought it would be a good suggestion.
I would like something like this too, but I'm afraid it won't happen. If players could control what was on sale what was on sale then I doubt Turbine would get full price for the items very often.
It should be only one time per month, a duration of five days ans some items blocked for votation, so Turbine would still have the control of the prices, and the players would have some good opportunities.