Casein not whey, but still a good deal. £40 for 10kg micellar casein delivered https://www.maximuscle.com/type/protein/powders/micellar-casein/ Buy 1 get 1 free deal. If you buy 3 or more price goes down to £20 per 2.5 kg, though I think this only applies to the chocolate mint flavour. I have no idea what the taste is like but it's worth a try. So you get 10kg for the price of 5kg. Delivery is free with min £40 spend.