Buying at great volume is usually the only way that you can negotiate a discount with suppliers, but if you have a good relationship, you can negotiate other deals. Leverage a discount in other ways, such as offering to pay early, or by bartering your product or service at the same discounted rate.
Furthermore, if you have connections with suppliers or customers who offer desirable products or services, you may be able to arrange discounts as a bonus for employees. Suppliers are often happy to offer products close to cost price if you have a good relationship, or you may be able to set up a discount exchange program with your valued customers.