AI buying is an excellent idea. It is a tool that could be used to stabilize every server's economy. You could even take it a step further and implement AI selling if there was a given item that was in short supply. Without AI trading I fear the upcoming 'auction house' as I would call it (sorry that name is embedded in me from other games!) will only make the current economy problems worse. As it stands, we can only really trade when we are online and actively trying to trade, and yet the prices for almost all resources are in free fall. An auction house will mean a much larger share of the active server base will be trying to sell their resources at the same time. With no demand for these resources, new postings will undercut the current lowest auction house posting and so on. Prices will hit rock bottom within 48 hours of any auction house going live.
AI buying/selling is not a solution though, it is a tool to maintain a healthy economy rather than a means to create one. My suggestion of a weekly adventure is another example of this. BB really need to address the fact that a server closed to new players is an economy killer and find a way to prevent this. I also hope that there is not a plan in place to open up server migration for $$ only. I have played games where this has happened, with people stuck on dead servers and the vast majority will either play less frequently or quit all together.
I would rather see a system where in active accounts are frozen, so freeing up space for new players to join the given server (basically allowing a server to be reopened to new players). Frozen accounts can be reactivated by the player registered to the account, and if their original server is full, they are automatically relocated to the most suitable sever for their level.