I think, realistically, you need to score at least 800k now to consider yourself "Top 100" material. There are a lot of scores that aren't on the official board (some Japanese players, Richie's killscreen, Victor Sandberg's killscreen, etc. etc.). The best I can determine, adding those scores would make 748,200 the #100 spot, and Anders Lasbo's killscreen #99. Certainly there must be a handful of other 700k players out there we don't know about. I think I heard that even BBH was a 700k player, but I don't think I've ever seen him play DK.
900k doesn't even get you into the top 50 and 1M barely gets you into the top 40.