Well the blu-ray currently sits at £23.57 on Amazon. So if you think of it that way you're just paying an extra £4.42 for the artwork and the different style of packaging. With the 5% code you're paying an extra £3.02. For me, True Detective might just be my favourite television show - so I don't mind essentially paying £3/4 for each episode. But I suppose it's all about working out how you feel about the price once the artwork is up and whatnot
And I imagine the Breaking Bad steels would perhaps be slightly more expensive if there were less of them maybe, say if it only ran for three seasons or something.