At our local art gallery, some of the artists get a little offended when you talk about commerce in art. We have a different gallery show every month, and I have done some videos of them. Mark has been in a few shows and has another one coming up in February.
The other irony of the Banksy stunt is that if he did sell his art at auctions and in galleries for hundreds of thousands of dollars per painting, he would not be the famous street artist that he is. In other words, Catch-22. His art would be worth nothing, if he commercialized it. But since he can't commercialize it, it is worth nothing, so to speak - in a commercial sense.