Shipping Cost - How can we get it cheaper than the consumer?

I know that UPS and FedEx have deals with high volume national accounts and shipping cost get drastically lower than the consumer shipping prices. But how can a start-up small business dip into the savings? It's all about volume, but how can I get volume with high shipping rates to begin with? Are there any consolidated shipping centers locally that get better shipping rates than the USPS? How do you all get better shipping rates? Thanks!