You need to be a t a guild store and scan ALL data of the items in your inventories + save them to your local savedvars to achieve this.
As the price can most likely change every second in your guilds you'd need to stand still at the guild trader and update it the same time
So: Not possible
The alternatives are shown in my above answer, as they get close to your request. They will show the most up2date prices in the world, lowest, highest and average.
TTC -> World prices of all users sharing the data
MasterMerchant: Only your guilds, with the data which gets scanned as you open the guild traders.