Truth is, the Cavs would probably be happy to get any value for Z. His contract is sizeable, and lasts for another 4 years. Most importantly, Z has a special trade clause in his contract. They would no doubt have to take a bad contract in exchange for Z, but perhaps they could get someone with a shorter contract that would free up some cap room in a year or two.
As for Basden, he will probably not make the team. His contract is not guaranteed, so the trade was probably really designed to help the Cavs avoid the luxury tax. And, of course, he's a good practice player to bring into camp. Basden is known for playing tough perimeter D, and for being a quick, athletic penetrator with solid ball handling skills. His shot is suspect, but aside from that, he is remarkably similar to Shannon Brown.
No doubt the Cavs should be thinking that they'll need youthful defenders to guard the likes of D-Wade and Gilbert Arenas. This is surely the reason they are willing to give up Damon Jones despite an organizational philosophy that generally favors perimeter shooters. So one scenario is that Basden plays "Wade" in practice and then gets released. On the other hand, there is the very slight chance he could play himself onto the team. Obviously the second scenario would be much more likely if the Cavs are able to move one or more of the Pavlovic/Newble/Jackson/Jones bunch. Either way, its a win/win situation for the Cavs.
I can't help but think that this move is in some way related to Lebron signing the shorter contract extension. It's the first clear indication that the Cavs are willing to sacrifice a player with a much higher upside in order to improve their current situation. The drafting of Shannon Brown could be viewed in a similar light, but I could argue that one either way.