Auction house is a premium plugin that is featured on many servers. I am trying to figure out how to link the auction house to an npc. I run citizens as well, but I can't figure out how to tell the NPC that he is an auction house haha. Any ideas?
So from what I can gather, you want an npc (Citizens) to bring up the auction house when you right click? That's how I correlated it anyway. If that's the case, it should be a relatively simple task of including this add-on plugin for citizens that allows the execution of commands through right clicking. That is the easiest/simplest method I can think of.