I have used FedEx ground. Here's how I did it:
I got a 4 ball box, and 4 1 ball boxes from the local pro shop. I filled 'em up, and shipped them to where I was staying. Fedex Ground is very reasonable.
I put two 2 ball totes in my luggage, and checked my 4 ball bag.
This gave me a way to transport 8 balls when I got to where I was going.

Then when I was all done, I did it in reverse. I had FedEx pick up the box to ship.

Good luck!