There is new pricing for Premier service plus for the home edition, which should lower the cost of ownership for many people to a very reasonable level. I have been paying for a commercial license (Premier Service) for many years, and will continue to do so because of other perks. However, the cost is trivial compared to what I can do using Wolfram Language on the desktop with all the bells and whistles.

The student versions are dirt cheap when compared to books, graphing calculators, etc.

There is also the Raspberry Pi, which is really cheap but which requires a bit of tech savvy.

None of the alternatives (CDF, etc.) in my opinion come close to providing the functionality of the full Mathematica.

I'm in agreement here. While there are a lot of things in the documentation and lots of 'neat' examples, they all cover elementary applications. I frequently have to contact support to get clarification or hints. This usually works -- some great ideas have been returned -- but it would be better if there were more examples and more details of the internals of Dynamic.

When Mathematica has a book (last version was version 5), there were chapters about theory that were quite long and detailed. Most of this documentation is still useful -- which is why I still have the books -- but they do not cover anything newer. This includes Dynamic and Manipulate in version 6. It is possible that this type of long discussion does not fit into the electronic documentation, but it should be possible to publish monographs or other specialized documents for advanced users.

I think quite the contrary, this is one of the best areas covered. The doc's page on Manipulate links to 5 very extensive tutorials. Plus Manipulate and Dynamic pages have numerous examples. And more than 10,000 examples on Demonstrations.

Bjorn Tipling, the author of the post If programming languages were weapons, would possibly answer "yes", as he sees Mathematica as "a low earth orbit projectile cannon, it could probably do amazing things" ;-)