From the Script: SLIDE 64 - Compiler/Tools Cost

Here we see that, regardless of the size of the staff or the number of licenses required, Ada compilers and tools cost almost double that of C++ for the Rational Apex.

Exactly the opposite is true for the SGI C++/GNAT - where Ada is half the price of C++.

And, to be comparable with the Ada tools' built-in checking, we have to purchase a tool like Purify to use with the C++ compilers.

The bottom line is that it pays to shop around. It isn't true that Ada tools are always more expensive. But it's not true that they are always less expensive either.