Wait! I know what you’re thinking… if they add this option it would reduce the chances of people buying more expensive stuff due to convenience and the market would be a competence of who’s selling cheaper, the prices would drop and the economy would collapse… well, sorry to brake it to you, but we’re already at this point! This option would help the cheapest product to sell FASTER and that would increase the chances of the next in line to be sold, and we could probably sell all the stuff on only one retainer, and also this would ONLY affect the stackable items, armor/weapons and any non-stackable markets would remain the same.
This is just my humble opinion, this idea might as well be very wrong. However, as I see it, it might help a lot on the economy of the server.