Kim Kardashian -- The World's Most Expensive Gym Bag

When Kim Kardashian goes to workout her million dollar booty, she doesn't just throw her sweaty rags in any old duffel -- she carries the world's most highly coveted handmade leather purse ... the Hermes Birkin.

Kim left a Beverly Hills gym on Thursday holding a black Birkin, which can cost anywhere from $9k to about $150k ... just ask Rick Yune​.