Hi all,
In case you're not attuned to things financial, go
here
My simple definition as it relates to this game: buy items from one guild where they are cheaper than in another guild.
We're allowed to belong to up to 5 guilds. The addon would have to scan the guild stores. Then it would need to suggest items that are common to two or more guild stores. It would then allow you to buy the cheapest one. You would then list it in the guild store with the higher price.
I have no idea if this is somehow forbidden by the TOS.