Presumably you "believe"........
ie You know and understand how GOOD CM is beneficial to an organisation.
Then your "job" is to sell that knowledge and belief to the bean-counters in the various organisations and also sell yourself!!
Some open source tools are good (enough) some are actually quite decent (when used well).
A CM tool (on its own) has NEVER been the Silver Bullet!!
Good process, Procedures and general good practices have always been a good investment (often alongside a good tool/suite).
SVN chucked into a bucket in a free for all for any/everyone to do what they want is no better (or worse) than PVCS or SourceSafe or Harvest etc just dumped onto a desktop without setting out good practice etc first.
It might be cheaper to install but the long term cost of bad practise will be just as bad!
So sell the benefits of doing it well/properly (and your services in doing it) - then you'll be laughing!