These were dug up in Egypt, where the archaeo-protectionists like Dr Hawass hold sway. Collectors will never own any these coins, because collectors are The Enemy. These coins will all wind up in a museum, whether the museum can afford to store and display them properly or not.
Indeed, coins like this are dug up in Egypt all the time. I own two, though mine are from the time of Ptolemy VI not Ptolemy III. The only reason these made the news this time is that the archaeologists got to these coins before the looters did.
Curiously, the picture included in this article (and in the articles on this story on other news sites) doesn't actually show what the actual coins found and described look like, with the portrait of Zeus-Amun. The coins under discussion actually look like
this. The coins shown in the news article depict a woman; presumably they are scarcer types from Ptolemy III's wife,
Berenike II.
