For those with a sweet tooth, these are even cheaper than the recently posted amazon deal (which worked out at 43p per bar), which was already a good price.
These work out at 40p per bar.
I gave the 18 bar price so people could make an easy comparison to the previously posted deal. However, the actual deal is 3 bars for £1.20.
Available in store or online (please don't travel to the shops just to buy these).