This is done.
http://antihax.net/arbitrageCalculator
Let me know if there is anything you would like to see changed or added. It will collect data from the addon
http://www.esoui.com/downloads/info1...DataRelay.html and update automatically with new observations from the guildstores the user visits. There is a 2 minute cache on any query so do not expect it to be completely real time since there are some calculations going on in the background.