I am occasionally frustrated when I see people selling a Z on ebay, in particular.
Might I suggest you sell the accessories separately, apart from say a case (which is good for protection in delivery). You'll get a better price, as firstly people with a Z already will compete to buy, and secondly, people always treat accessories as a kind of freebie/bonus.
There have been a number of times when I've seen Zs with LOADS of accessories go relatively cheap, such that I have nearly bought them anyway for the value of the accessories, and then I'd re-sell the Z on its own.
Damn, just gave away my secret strategy!