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.
Problems in Harry and Meghan Marriage
So it begins….. Streeting resigns
By special request, let’s discuss our favourite Classic Music and why?

We don't have an Asda though!