It is feckin ridiculously expensive stuff - worse than Gas. I'll never buy it at full price if I can help it. Did have a surplus supplier who did 3 tabs for 50p (bargain - 1.e. = £2 a box of 12) unfortunately that was a finite supply.
Army Hexamine is the same efficiency/density and a fraction of the price. Pity it's a funny size. Depends on yr stove - I use a dish from the base of a drinks can glued on the base of my Starlyte so not tab size dependent like some other Esbit Stoves.