Is this the right time to buy it?

[Deipotent]

Check the "Update Size and Frequency" section of the following FAQ post and you will see that major updates have been released every three to four years:

If you look at the history of Directory Opus, people were only asked to pay for major updates every three to four years. (Most recently: 2001, 2004, 2007 and 2011.

with the latest version 11 being released in March 2014. This is not a guaranteed time-scale, but Opus updates are very generous and include both new features as well as any bug fixes. Support is second-to-none as well.