The rip-off of the century

I bought a full Soda stream setup at the beginning of the year and went this past Sunday to get my first gas cylinder re-fill at my local Pick and Pay. What a rip-off, they wanted R135.00 for 400 grams of CO2 gas which I refused to pay. Does their gas contain gold particles in suspension? I went home and dumped the whole lot in the dustbin. If you use 1 cylinder of gas and 4 mixers and manage to get the maximum 45 litres it costs around R340, that's R7.55 / Litre, what's the point, it's cheaper to buy ready made !!!!