USP and FedEx are almost equally the same, if you have an account you can probably get a shipping discount. You can round up a $50 to $120 for overnight and $30 for ground service. USPS priority is the most affordable but you can some times find your self struggling with delivery confirmation or zone coverage.
Online Cake Delivery Services: There are companies that do provide this type of service and charge a reasonable amount for their services. Normally cakes are more expensive on websites and you will see shipping charges rather cheaper than shipping your own cake. Online cake shipping companies get special volume shipping deals and as a result customers get cheaper shipping.