No, they haven't been making prices go "sky high". To use your example, prayer pots have kept a very stable 9.5k average this past month - hardly unbuyable, and certainly not for weeks. You said yourself above that these clans target items that are used commonly by the vast majority of the population. By creating a tax on these items after they have been allegedly "merched", how would that leave the "everyday user" alone, if they use these items so frequently? Sorry - I thought you were advocating to reduce manipulation? How would informing more people about how to do it stop the problem? Ignoring the abuse that would stem from such a feature, how exactly would one go about "proving" that an item has been merched? Items have natural trends of rises and falls that could quite easily be confused with some sort of manipulation. Going back to your first question, yes, they can be stopped (not using the methods you've listed above), but, no, they shouldn't be.