Whats the most economic way to ship a large container from coast to coast?

UPS and Fedex now both have freight divisions. they may be cheaper than commercial truck freight lines. often you can take these packages to a UPS or Fedex store and drop them off. Call first. Sometimes their freight operations have different pickup locations. you also may be able to ship these items to a UPS or Fedex store near the destination and for a small fee they may accept shipment on your behalf and hold the items. call the store first. this may be a store by store offered service. Lastly, your question implies that you are shipping a liquid. all carriers have special packaging and handling rules for liquids, even simple water. you may need to have a material safety data sheet (MSDS) to travel with the shipment. the supplier of the product must provide one if requested. Good luck.