Very important question, and there are several, several answers. Most pressingly, by cutting out the middlemen and buying directly from Luke on this store, you get to pay less and he gets to keep more. There are lots of other cool perks, like the fact that buying here opens a direct line of communication between reader and author — not to mention the part where you're actually buying your eBook files rather than merely licensing access to them (as you typically would be on most major retailers). But in the end, it mostly comes down to that simple idea: Buying direct saves you money while also maximizing your support to the author. It's a win-win! (Just not for the big retailers.)