Cores are plentiful on eBay but good descriptions are rare. This seller says he has no keys for any of his cores yet he shows one core with a key in it and six more Best keys nearby. Given the seller's ID and his high feedback, my first guess is that this guy sells a lot of stuff that he knows little about and, therefore, cannot give a straight description of what he is offering.
I noticed that at least two of the cores have keyways that are turned. This suggests that those cores have no pins at all. A core without pins will provide no picking practice at all. The seller offers no explanation. Are these the only unpinned cores or are they all that way?
My suggestion is to keep looking and find a seller who is a little better at communicating what he is offering.
