I personally think the painting is worth more. It's an absolute steal for $450M. I mean, you have all sorts of startups with funky names these days with no profits being valued at hundreds of millions. In contrast, for a truly classic masterpiece of an art, why wouldn't I pay so much?

This is not so much of marketing, but rather the (perceived) value. It's a classic piece of art, it doesn't need any marketing. Not a website, not a .ly domain, not an appstore app. It can sell itself like it has. That's art.