Buy a 200g jar of Kenco and get an extra 150g refill sachet free.
So its 350g for £4.88 >>> £1.40 / 100g
This is a little bit cheaper than the recent offer on this site, for
Douwe Egberts 200 g BOGOF meaning £1.47 / 100g
Kenco tastes nicer than Douwe Egberts too, so that's a bonus