If open source alternatives are not available, buy or build your own tools. (entrepreneur.com)
And if there isn't, a similar open source alternative comes out soon there after. (slaw.ca)
I'm primarily a MS Web / Windows developer so I use Dotnetnuke a lot, but non-MS open source alternatives like PHPNuke, Drupal, Mambo, OpenCMS etc are just as good (OK John A — better). (climateaudit.org)