It used to be cheaper. But they must have had problems garnering business or fighting voting ring detection systems. You'll notice there is a wider array of sites listed now than before. Lots of new video sites and things like Kongregate which weren't there back in 07 when they were very busy are listed now. For example, Hacker News (not listed, but surely is vulnerable to this sort of thing), about 4-5 votes within 1 hour and you're guaranteed front page. s&p aren't the only ones offering services in the market of course.