Thanks for your comment...and to all the others on this thread for the help.
The reason we like Open Source is NOT because we don't want to fish out $300 for a CMS.
It's because effective Open Source projects have a large and robust community behind them, which means that:
1. They're not dropping out when the product becomes less profitable...if some drop out, others take over and
2. There are many people looking at the code and fixing bugs.
So that's why we'd prefer an Open Source product. But like I said, we are considering Craft.
We looked at Drupal 8 a little and spoke to some people in the organization who are using it.
Our concerns are:
1. the need for full-scale developers when working with Drupal. We don't want to the site maintenance to be dependent on hard-core coders long-term, since that requires always hiring programmers rather than lower-level web developers.
2. Drupal upgrades. We've heard that it's very difficult to upgrade between Drupal versions, as many of the plugins/modules don't get upgraded, at least not right away. So you can be left with a Drupal site that can't be upgraded without losing functionality.
Thanks.