I would be able to make this work myself, why should I buy it?

Bruno Munari, a famous artist, philosopher and cultured man, used to say that the correct remark would be "Even I would be able to reproduce this work", because it was actually already made by someone else. Today, someone would even be able to rewrite a piece of the "Divina Commedia", a poem by Leopardi, a song by Elvis Presley or The Beatles: the hard thing was to write them at the right time.
As a matter of fact, an artist like Lucio Fontana, who became famous for having cut canvas, was not celebrated because of the technical difficulty of his works, but because of something more, which has to do with the idea he was able to express simply but in a very strong and incisive way: through a cut!
Contemporary art (but also the art of the past) isn't just a container (the work), but is also tightly connected to communication and messages (concepts); what we should judge, is not the technical difficulty, but the beauty, cleanness, refinement, emotion, strength, effectiveness, the ability to communicate something important.
We shouldn't forget that almost every artist of the past didn't realize their masterpieces alone, but were often helped by a team of painters and sculptors, who used to prepare most of the work, which then the master used to improve and finish off.