This may not be quite as good as the 3 for £10 at Asda but I found the selection at Tescos better. For instance, Tesco had the new Flat White variety. As someone has already said, it's an ok deal if you're in Tescos anyway.
I can't see them this cheap except for some subscribe offers.
Asda do a compatible variant too and they're very good! but no milk capsules, which are pretty dire anyway. Fresh milk is much nicer!
You can get 3 boxes for £10 in Asda
Great deals elsewhere too by the looks of it. But this is great if your a regular Tesco Grocery Shopper.