If anybody is looking for a cheap Helinox-a-like chair, Aldi are selling their £17.99 version again from next Thursday. I got one last year, and get on well with it.
I bought a pair for a basic backpacking trip in the Dales over the Bank Holiday weekend. Light (comfortabye less than 1kg), compact (fits down to the size of an upper arm), and has the feel of being reasonably robust (survived my 90kg of toned muscle, ahem). Only minor niggle is that it is a tad compact/tight fitting (unless you are less than a slightly strained 34" waist) and a prescient worry that the elastic snapback cords will fray and snap over time.
At £18, I can't imagine £-for-£ that the Helinox they are based on are so much better as to need spending +5 times the price.