But there are two inconsistencies here.
First, Nicalis who is publishing Binding of Isaac has the game only a few dollars more. They say the physical release cost is $4-$5 more. Nicalis is publishing only in America which may be why the costs are what it is, and why Eurogamer didn’t talk to them since they aren’t properly ‘European’.
Second, physical doesn’t have to be retail. Physical can be mail order. We don’t care about the game being sold on retail, we just want a physical option. If the game is offered physical by mail, it will sell, and it can be a higher price.
Do you know the surest way to get physical carts a separate price from digital? Declare the physical carts to be ‘special edition’. It would be TRUE.