Hi Paul
My Open Source CMS of choice is Joomla. As you indicated, you'll need to be able to set up the server and be a bit of a sleuth about customising it, but, as they say, the price is right for the underlying system. Also, there are heaps of free templates and plugins and lots of resources for setting things up. Here are three Joomla sites I've created:
OK, I'll post this now because I'm heading off, but hopefully this will at least get you started.