Recommendation for packing/shipping large speakers

Then the ups golf club box is perfect size, buy direct at any ups store. 
Wal-Mart for bubble wrap, cling film, peanuts, maybe packing paper too.
I have shipped many speakers I sold here and eBay using same method.
Last ones were b&w 804d.
All arrived safely.
I wrap the speaker first then slide into the box or slide box over the speaker. Lots of packing once in the box to stop it moving around.
You have to make it so the only way they could damage it would be to run over it!
Also lots of fragile and handle with care signs on box too.
Not sure if they take notice but in event of damage it helps your cause on any claim!

Call the manufacturer, you might be able to buy original boxes & inserts from them. 

mrboxonline.com will sell you custom made boxes and packing materials very reasonably priced. I purchased double boxing, sized to order, for very large Dunlavy SC-IVa’s I sent to England. 

That is useful to know ncarv, filed away for future reference
Thank you

Plycon is a vanline that specializes in feagile and high value items (think priceless marble statues or paintings).  They pick-up with a white glove service, pack, deliver & unpack, all the while your item is completely insured.  They’ll even deliver inside and place on position.