Tesco, aero type £6.00 per set on regular in store deals. They last about 2 years, that's Six to eight years worth of fresh wiper blades for the cost of Bosch equivalents.... I've been using them for the past 4 years....They work exactly as they should... Enough said really
Anyway, haven't seen any of the dual sided yet here but will keep an eye out.
Noticed the link you gave said "made in china" though, I've obviously worked on the ones "made in belgium" and that's what I've had in my hands earlier this week for fitting on a client's car (not dual sided again, still the old shape)