I'm surprised, but not disappointed at all, that ebay seller sure is smart. I thought downloading it from here for free would be more appealing to people and they can then easily make a wallpaper out of it for themselves, but if they want to buy it from ebay, so be it. Who am I to say otherwise.
Can I use it?
Yes you can use it in any way you want it, some guy even asked me if he could make a T-shirt out of this, which he did and it turned out pretty cool actually.
Yes! This! ^