Are they "collectors" or "investors" or "speculators"?:
http://www.google.com/hostednews/afp/article/ALeqM5jfWR4N9gZaDCVTpE-dfNCrJATqQg?docId=CNG.2700a1814657e888bc9b9c0864a99dad.3e1 The show also sought to roll back the commercialization and gentrification of graffiti. This is an age when street artists like JR and Britain's Banksy have global recognition and collectors are pouring in money.
