Marketplace
Description
A separate map that could be accessed by a warper in each city. It would be divided into small "stalls" for shops with walkways for buyers inbetween. These stalls could be accessed only by merchants, and they would setup their shops there. Most of these places would be free of charge to access and setup shop. There would also be private areas that could be rented (or maybe auctioned? with the highest bidder winning the spot each week) for a price. These private spots could include small prime locations close to the enterance, whole bigger areas where you could setup like 10 shops with only your merchants being there. Rent would have to be renewed and paid every week or else the spot would be available to rent by anyone else again.
Rationale
Lots of shops in prontera suffer from being overlapped with each other, hard to see, long distance from the main square ... People fight over the best spots by either buying out someone elses shops and taking their spots or placing clearly overpriced items to save their spot. By making a very uniform map where every shop would be equally visible, with best locations close to entrance up for bidding (or renting), i think this solution would alleviate if not all, then most of the problems with the current marketplace. Also private spots would function as a zeny sink.