About a year ago, I bought a pair of used Vandersteen 3A's from Audio Connections in New Jersey, and they shipped the speakers using a trucking firm that has given them good service. You might call Audio Connections and ask them for the name of the trucking company they use.
Not sure where you live but check into an Air Freight company at your airport. They will probably be faster and cheaper than ground service. I sent a pair of JBL S8R Olympus' (250 lbs. each and big) 1500 miles using air and it was the most economical way to go. Believe it or not.
I had a pair of Martin Logan SL3's shipped air freight to me. Had to pay the seller 1st, then pick up at the airport. Shipping was far less than UPS or Fedex. Airlines won't accept speakers with "magnets" as they claim they will upset their navigational equipment.