Do people still pay for screensavers? I mean, with today's technology, they are no longer necessary to prevent monitor 'burn-in', so $10 for a pretty little animation, I think, is too much. If anything it ought to be free

While most modern computer monitors resist burn-in pretty well, some displays are still prone to experiencing it. Plasma television screens can burn-in, for example, which could be an issue for a home theater PC. Current OLED screens, such as those used in many portable devices, are even more prone to experiencing burn-in, although they're not commonly used for desktops and laptops quite yet. When the price of large OLED displays reach a point where they become more marketable to consumers, screen burn-in may become a more common occurrence.

As for screensavers, they've always been more of a novelty item than anything. You can, after all, just have the screen go blank or switch off when not in use. However, many people like them because they provide interesting things to look at, allowing the display to double as a sort of animated picture frame. Whether someone is willing to pay $10 for some animated art to look at is really just up to their tastes, and how much disposable income they are willing to spend on such things. People buy various wall hangings to decorate their homes with, after all, and this isn't really any different. Whether the art is something that people would be willing to buy is the bigger question, but not one that's exactly related to screensavers in general.