I've joined forces with the hobbyDB team to create a database of every Starbucks Mug ever made! You can use hobbyDB to manage your collection and wish list, show it off, find values for your mugs, and to trade, buy and sell. We currently have four volunteers and would love to have more join the team. If you'd like to help, contact the guys at hobbyDB.
Starbucks City Mugs 
Where i can buy this tumbler?
I would try to find it online but you do have to be careful because it seems some seller from China are selling fake mugs and tumblers. Best of luck!