I wouldn't necessarily call it "unsafe" to purchase (he says picking his words very carefully!) but I don't think it's been presented on ebay very well...
You could put this down to the person not really knowing, or having experience with, what they are selling, but the fact that he's been selling these for a while and others have asked questions and got some "interesting" replies kind of suggests otherwise...
It's very easy to get excited about a cheap item on ebay that seems to be a bargain, but on closer inspection (as with this and the caps/springs and the previous one with the wear marks on the basket) you sometimes need to look a little closer.
If you are considering a slipper clutch, you should have a look at
http://www.tecmoto.co.uk/ as they sell a range of complete clutches from around 540, including both STM and Bucci.
(although I can't get to their site at the moment to confirm prices!)