I haven't found a place outside of Germany where Rimowa is cheaper. So I'd rather stick to the German stores. The World Shop really just makes sense if you want the blue Bolero or don't have a chance to hit another Rimowa store in Germany.

The best deal on Rimowa is usually at the Hetzenegger store in Munich (either Stachus location or the other one) If you pay with cash or EC (ATM) card instead of credit card, they will give you another 10% discount off their original very competitive prices.