I Navis Pack and Ship a little over a year ago to ship out my Revel Studios. They were helpful and reasonably priced.
(By the way, you can save money if you ship terminal to terminal.)
Here is a link to their website:Navis Pack and Ship
However, regardless of who you choose to move your speakers, make sure to do the following:
1. Get insurance. (These guys are used to moving big heavy and sturdy crates. Speakers, amps, etc, are somewhat fragile, depending on how you pack them, and these guys move freight, so don't expect miracles. Be a Boy Scout, since accidents happen, so "be prepared". Also, make sure that they realize that if one speaker is damaged, they have to pay for both. (If your speakers are out of production, what the heck are you going to do with one speaker?!)
2. Since you now realize these guys move freight for a living, pack your speakers up like freight.
A. Put the speakers on a pallet. Have the freight company strap down the speakers to a pallet. This means that they will use a fork lift to lift and move your speakers. This is both good and bad. Good from the standpoint that your speakers will always be moved with them standing upright. Bad from the standpoint that the forklifts have, well, forks, which could stick into your speaker boxes. So, you'll need to armor your boxes...
B. Have the freight company put a layer of double, or triple, strength cardboard around the speakers, (on all sides and on the top, just in case something small gets shoved onto your pallet of speakers). This will armor your boxes so that they will withstand normal wear and tear on their journey across country. (When my speakers arrived at their destination, the buyer thanked me for putting on the armoring cardboard, as he said there was a good sized dent in the side, where something, (one of the forks?), had hit the cardboard armoring. But the speaker boxes inside were safe from harm.
Well, those are my words of advice.
Good Luck shipping your speakers!