There's definitely some sort of dose/ratio thing with chocolate. Even so, I find the higher quality stuff works out cheaper, for my own preference anyway. 4 squares of Green & Black's 85% will do me for a day (I make that 12p a day @ £1.69/bar), or 12 squares of their milk chocolate (33p) or a whole Galaxy Ripple - about twice the weight - +/- 50p, depending on the retailer. Meanwhile, Thornton's chocolates are vastly overrated IMO, and 2 - 3 dark chocolates out of one of their boxes is enough to make me want to heave.