That excuse is very VERY lame. It just means, in my opinion, that the teachers are lazy ***s. The cheapest language they could switch to... php. Full very detailed documentation, any basic text editor will do (you don't even need an expensive office suite). How about C# or C++, the microsoft visual C++ / C# suite has a free to use (I do believe only for non-commercial use, such as eduction) version called the express edition. How about java, there are two fine high-end IDE's for it (netbeans and eclipse) with full documentation online. If the microsoft thing has a reason not to use, java has similiarly powerful IDE's.. Than there is python, also no costs associated with it.. excellent documentation online, also just needs a text editor...
I see absolutely no excuse why they'd use VBA as opposed to the above mentioned languages. Funny part is, I know there are many more languages that fit into this pattern, though I simply have never been exposed to them. In fact, I can't come up with a programming language that inherently has costs associated with it.
So in short, there has to be something else up with those teachers, because the argument provided holds no ground.