Varrek

Location
is the Mystery Merchant you will find in Val Oriyn Area.
 * Amadjuak Trading Post
 * Domare Outpost
 * Hulran Watch
 * Outside Highwatch North Gate near bridge
 * Trellum Consurgo Inner Ward, bit west from Macellarius Catacombs teleportal
 * Khirian Outpost
 * Thaumetal Refinery teleportal in Oracle Cave
 * Mjusu Kraal, cave next to road when climbing towards Mendara Cavern
 * at Baraka Seekers' roadblock in north part of Spring Valley along the road to Highwatch
 * Arch of the Seeker at the entrance of the cave

Varrek might sell auto-looting or auto-gathering pet.

Mystery Merchant Shop
's shop information can be found in this list here

Trivia
The only Difference in the all of Arborea's Goblin merchants in the color of their backpack. Varrek has a brown Backpack