I just wanted to address the original question. Because all SodaStream machines are essentially the same, by this I mean they all fizz water to the exact same degree. The differences in prices are all down to exterior design and features.
For instance I have the newest top of the line model referred to as the SodaStream Power, see this review for in-depth details: www.slinkystudio.info/reviews/2015/9/15/sodastream-power-review
The reason I purchased this model is because it plugs into an electric output so it fizzes water to three different and most importantly exact levels by the press of a button. It's not cheap at £149, but looks lovely in white. Also the newer flavours within the UK are ridden from aspartame and many other bad ingredients. They taste lovely and I like a light fizz, which this machine does without me needing to guess or get it wrong.
I hope this is helpful.
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