They're only "worth it" if you get it on sale, 20%+. Otherwise you're paying a really big markup for the convenience of it already being mixed, and it isn't all that inconvenient to simply add 1scoop of whey, 2scoops of oats and 1/2 a scoop of dextrose into a blender/shaker and mix.
It costs more upfront to buy everything individually, but you get A LOT more for your money.
GN/MP have a January sale on at the minute, have a look at what they have reduced.