Well most players aren't changing out their glamours that often, so swapping out a piece every week or so isn't a big deal, even for 5-8K a piece. That might be a lot of money for some players, but if you're playing casually you probably aren't keeping up a glamour on more then one or two classes max anyway, and most players don't get new gear to glamour over weekly.
The inventory this takes up is a MUCH bigger issue, and something needs to be done to address it. Best option would be something that attaches glamour-storage to something external, like a vender, NPC, or something. That way they won't have to devote as many resources to storing your glamours. Your own inventory takes up a lot more resources due to it being updated every 15 seconds, I presume an NPC's inventory doesn't get updated nearly as often.
