1- great idea, and would add an outlet for money (limited outlet, but make the slots expensive, like 4 for 1 plat or 2 plat)
2- also great idea, takes care of the commonly requested shop/merchant/auction issue... except that at every xunlai there would be hundreds of items
3- great idea for another money outlet for the game
4- okay idea... I think it would be better if their was a special market district (as in 'part of town' not 'server') within each city where npc's set up, 1 to sell only runes, another only dyes, another only armors, another only axes/swords, another staves/wands... you get the idea. click on a merchant:
-list of all item groups (all of exact match items stack, similar items are near each other) Below each item stack is the average price of all items in the stack. Click one stack:
-list of all exact match items, arranged from cheapest to most expensive. This would induce competition for pricing since I could easily see that I shouldn't buy Joe-Blow's black dye for 3.8k when I can buy Shary Mary's for 500G. I think this would also make the market a much more interesting aspect of the game since you actually have to think through and struggle in the economy, whereas now it's more a game of "how much can you get away with/ can you find somebody to buy it for this price."
EDIT: perhaps the first money sink would be to buy a row of 4 "sale" slots for items, so that you wouldn't accidentally sell items you didn't want to you could buy 4 slots to go below your regular storage (broken by a small space) with a number to set at each slot, visible below the slot. Then you could buy other slots later to a total of 20 sale slots to compliment your 20 regular slots. If you wanted to use the sale slots for storage you could, simply set that stack of purple dyes to 20p each and then you could be sure nobody buys them

And if someone does, celebrate.
