I'm not a SORBS-hater, but I'd say that $451,000 seems a bit overpriced! How do they expect to ever get that level of investment back?
Gosh. our antipodean chums are mighty well protected (as their porn-finder general would no doubt view it.)
We long ago removed SORBS lookup from our spam filter because we judged it to be more trouble than it was worth. If it's been sold, perhaps we'll look at it again. First we'll give it five years to settle down.
We only give SORBS a very low score in our anti-spam here.
They even listed us on there a couple of weeks ago when a user's exchange out-of-office autoreply replied to a spam message... and getting off it is not so simple.
SORBS has an ugly "fuck you" policy for spamlisting. I found myself inside one of their listed IP blocks, and found out that they do not honor or maintain any kind of blacklists. This of course means that the only way to get "unblocked" is to pay their $50 fine to unblock the entire netblock I reside in, or wait for SORBS to auto-delist the block. The first option would obviously not work, as whoever's actually spamming on said block will keep on spamming, and get the whole block to get listed again; and the second one, well, I doubt the spammers will cease to spam.
Thanks to this policy, I've discouraged SORBS whenever I can. In these days of colocation and IPv4 address shortages, I can't really decide on who's going to be my IP neighbor.
The biggest joke of an e-mail security vendor (using the term loosely) buys the biggest joke of a DNSBL. They're made for each other.