All the info you need about the Heatstick here :
http://www.thegearcaster.com/the_gearcaster/2012/05/heatgear-heatstick.html
Main part :
Weighing 380 grams (13.4 oz)in total, the Heatstick package includes the heating unit itself, water bottle, sleeve, igniter, and a rubber shield. One Fuelstick weighs 93 grams (3.28oz) and will heat around 9 liters of water.

The Heatstick retails for approximately $415 and can be purchased from the Heatgear website. A pack of 10 performance Fuelsticks will add a further $80 to your cost.


So it will cost you about $1 per liter of hot water
after the first 9 liters and $415