ShipYourAquatics.com advertises its service as “20% off Fedex retail,” presumably by aggregating multiple shipments under one Fedex account to receive a collective volume discount.  Users can generate and print FedEx labels from home.  They also offer shipping supplies such as insulated boxes, fish bags, as well as heat, cold, and Phase/CyroPak packs.

Disclaimer: Advanced Aquarist is not affiliated with nor have we tried ShipYourAquatics.com; We have not verified the stated discount nor endorse their service.