On my server there is one person controlling the one star market by simply undercutting all the time (updating prices like every 10 minutes) using multiple characters as they have 5-6 retainers selling gear signed with their name. Because of this it is impossible to compete against such players for any share of the market unless you yourself are updating prices constantly.

I'm not too sure what the implications could be if there were a restriction on a time limit for when you can update prices, or if there were a listing fee, but something has to be done about this as it's annoying never seeing any of your wares sell.