Nakd bars 4 packs (and single bars) are currently on offer in a 4 for the price of 3 promotion, which gives a pretty decent price of around 51p each. I've put a link to that offer in here.
HOWEVER, in my local store (Baguley Extra) they had the Cocoa Delight single bars which were part of the 3 for £1.20 confectionery offer. The single bars don't seem to be online, and there was no shelf edge label about the offer: I only spotted it because I was getting them on scan as you shop.
OK, it's not the hottest deal in the history of the world and certainly doesn't touch the pound shop offers that sometimes come up, but 40p each is a decent price for these in my opinion.
No idea if this is nationwide or whether it's one of the traditional Tesco wild goose chases, but thought I'd stick up here in case it helps anyone.