I like many of the works of Banksy.
I can’t draw/paint, and admire the skill of people who can.
However, the works of Banksy are not the product of great skill. Many people could easily produce similar work. Such works should not be worth large amounts of money.
It was reported that London Zoo was planning to put a protective Perspex screen over a recent work by Bansky. To do so would, in my opinion, be a stupid move. It makes sense to put a screen over paintings that are the product of great and rare skill, such as Van Gogh’s Sunflowers, but Banksy’s graffiti is street art. If it begins to fade with time, then the artist, or indeed someone else who is capable, can touch it up.
The claim that recent works of Banksy appeared in London without the knowledge of anyone else is very dubious. You can paint something on a shop in densely-populated part of London without the owner’s permission, with no-one else knowing that you are doing it?