As a current .net developer and a former E-Zine editor, I can give a few points on my experince in this area.
The type of CMS needed for a Non-Profit org is dependent on the use and importance of the Internet application in the org.
DotNetNuke and
Rainbow is a simple effective solution.
While some developers still argue these are not "True CMS", they still work quite well for small to medium orgs as a CMS. It is easy to set up for different roles for content management, and takes very little training and no technical expertise to manage content once implemented.
They are open source so they are free, and most medium to large hosting companies’ offer them as free add-ons to hosting plans. Your webadmin can implement them with a few button clicks.
Skin Templates (Look and Feel) can be purchased from $35 to $100 from a host of places on the internet. Custom Skin Templates run between $350 and $2,500 depending on requirements, the average cost is around $800, from a qualified developer in your area our on the net.
If your Internet content and management is integral part of you non-profit's mission then you should consider a commercial CMS.
This a list of all CMS (OpenSource, Freeware, Commercial)
Some of these systems can be very expensive. I often tell my clients, when it comes to tech it is usually better to spend more in the beginning on the more expensive reliable and proven software and hardware systems, then to pay more later on for tech-support and down time with the less expensive software and hardware systems, which almost always is more expensive in the end.
On the content, always have a review system in place before posting. It is easy to miss the simple mistakes and those are the ones that stand out the most.
Bryan