Up & Go breakfast drinks are half price, 69p at Waitrose. CheckoutSmart and ClickSnap are offering 50p cashback too, and you can claim up to ten times. That would bring the effective cost down to 19p.
I wouldn't pay full price for these, but 19p is very tempting...
Cheapest elsewhere is £1.38 or 5 for £4 at Asda.http://www.waitrose.com/shop/OfferDetails?offerId=13214360
Available flavours are: vanilla, chocolate, strawberry, banana & honey, mixed berries.
Thanks to footydownloads: "You can claim 50% back from Shopmium as well as Checkoutsmart which makes it free with profit."
UPDATE: It seems CheckoutSmart have stopped the cashback offer. Make sure you check in the app before buying!