Reddit's actual CPM is 8$. One of the admins said that Conde wants to keep it a premium brand and they don't actually set the CPM. I'll try to dig up a link. It's also why there's tons of cross reddit advertising, and adverts that are paid are only seen for a tiny bit of time.
Pretty depressing seeing comments like "Also there is no way a website has a $8CPM" and wondering why people who don't know what they're talking about keep on talking. I sell at double that rate for smaller sites on a daily basis ;/