If you buy a single domain license, you'll get a coupon for a very good discount on unlimited version
BTW, it's very stupid to compare the CyberSEO Suite of 2008 (as far as I remember that version even had no it's own XML/RSS parser) and CyberSEO Suite of 2011. It's like to compare a bicycle and Maybach
The script is continuously developing and all the upgrades (past and future) are 100% free for all customers.