World of Warcraft has sold 8.6 million US copies to date
According to recent NPD data, World of Warcraft has sold 8.6 million copies since its launch in November 2004.
Average sale price for all versions was not provided, but Gamasuta has figured that with an average $30 for each unit sold (core retailing at $19.95; expansions for around $39.95), ActiBlizz has netted $258 million total from the US end alone.
This does not take into account the numbers over in China, nor the $15 a month that users pay for a subscription but with 11.5 million subscribers - that's a bog load of money right there.