Re: Using Vendors for Storage.
In Ultima Online, the npc vendors charge a fee for their services. The fee is taken out of the player's bank funds each real life day, whether the player is logged on or not, and the amount taken is related to the prices of the items on the vendor.
This system does not prevent UO players from using their npc vendors for storage, but it does ensure that they must work to maintain such storage, by earning the gold they need to keep their npc vendors from quitting due to lack of wages.
I am not sure how this could be implemented in Ryzom, however. Perhaps a better solution to storage issues in this game would be to allow people to craft from their apartment inventory, increase the BULK for apartments, and perhaps allow us to buy beefier packers not meant for travel but for increased storage capacity (they would carry more bulk) and have us need to feed them to keep them from collapsing in the stables.
Perhaps npc merchants should charge a non-refundable consignment fee for any items over a certain bulk, as well.
In the mean time, calling the practice of using inflated prices to protect items stored on vendors from being sold is not an exploit. It's a clever use of the game mechanics, which were designed and implemented correctly but apparently could use some improvements.