People purchase art online in almost ridiculous amounts. Artists offer their works for sale, either as prints or other media, and their fans buy that art in order to not only support the artist but also to have something that they like around them. As artists become more comfortable in selling their prints to make a living that is a trend that can only continue.
All this means is that a collector needs to pay special attention to the art he likes and be willing to do some homework in order to make sure that you have the right artist. Also, be prepared to buy some frames as prints rarely come with them. just watch out for frauds and tracers, and pay attention to the quality of the prints and you should be able to grab some really great works for your walls.