If you're moving furniture, just have the moving company wrap the hard cases in thick blankets and make sure you declare the brand, model, serial number and value of each bass in the insurance form. If you're checking all that gear as baggage...you'll be spending a fortune. I'm guessing around 120 to 150 dollars per piece, plus excess weight for the cab and racks. I'll take a wild guess at 2000 dollars.
Alternatively you can either freight it all in a nicely built wood cage on a pallet, which would cost you under 1000 bucks for the whole thing, insured and all...door to door. Or have a specialized firm do it: these guys
seem to offer the same service. MyUS.com
is kind of expensive.