The Green & Black's is usually £2.01 but are now on offer 2 for £3, so they work out to be £1.50 each.
The Dairy Milk is usually £1.99, and too is on offer 2 for £3.
I did a quick check, and Green & Black's is £2.01 in Tesco currently.
This is part of the 'Fairtrade Week' promotion. I can't remember when it ends.
ps: Just realised, I work for Waitrose, so this may count as self-promotion, I hope this isn't against the rules. At the end of the day, a few people going and buying this isn't going to benefit me.