What are the key areas which will give you upper hand on supplier for rate negotiation?

Key Areas in supplier rate negotiation goes beyond heap cost/price.  Its the Over-all:  value for money,delivery /leadtime, payment terms, after-sales service, quality, lifetime cost of product/service, and of course, i would add, the kind of supplier - if this one values continuous improvement not just on products and services, but most importantly, the people handling your business.. 

Agree with you dear Domimique, almost now a days to take care of the long relationship between the suppliers and thecompany it self almost every body care about what they will pay for leaving the quality, delivery time, right timing to deliver the products and after sale service to be included while if they add to there consideration that suppliers can be used as free warehouses which mean in the other hand a great cost reduction and we can take an example on that DELL the dont have any products warehouses whish assisted them to reduce the product cost and enable them t compite with high orofitability margent.