Re: How to ship a guitar without a case
+1 on the double-boxing. Last time I bought a guitar on eBay, my wife was like, "So you're keeping the guitar -- we can throw the box out, right?" I said, "Gaaah! No! Never throw out a guitar box". It's always good to have one around for out-bound shipping. I also think the stores are reluctant to give them out to their "competitors" - eBay sellers.
However, last time I sold a "good" guitar on eBay (an original '74 Tele Custom), I went out and bought a case for it, then stated in the auction that it would be shipped in a brand new case. People then bid accordingly, and I presumably got my money for the case back in the final price.