ArtRage 2.5 Deluxe is a boxed edition with added content, tutorials, stencils and whatnot. It is going to be available for sales in actual physical stores, through a publisher.
The core application is the same as ArtRage 2.5. The higher price point is a reflection of the additional content, and the costs associated with geting a boxed product into physical stores.
You're correct in thinking that internet-savvy people would be able to purchase ArtRage 2.5 Full or Plus edition online and save some money. However there is a large segment of the target audience for ArtRage who are unable to use the Internet to make a purchase. So the ArtRage 2.5 Deluxe edition in stores is now available for them.
AndyRage's mantra for graphics engine code:
"Sure - how hard can it be?"