There have been many dillusional people on these forums over the years who have said that a gold plated HDMI lead costing over £25 will give better picture/sound output than a basic one costing £1. It is absoulte insanity, a digital bit-stream, when interfered with disappears or 'blocks' as 'bits' of data are lost'. Pretty much every cable is specified well enough to carry a digital bit-stream well enough not to 'block' no matter what its made out of.
All you need to look for when buying any kind of cable to carry a digital bit stream is that the PVC of the cable itself is reasonable quality and that the plug on each end is terminated well. Even third world countries can manage to make cables of this quality these days so it's unlikely you'll get a bad one even if its only cost £1.
The claims that places like Currys make regarding any form of technology are outrageous and any consumer who feels they have been duped should make a complaint. They play on people who don't know any better and that's how they made billions back in the 80's and 90's.
Walk into a shop like that knowing what you want to buy and your asking for trouble, you are more likely to come out with something the exact opposite of what you wanted, costing twice as much or bundled with a load of extras you'll never use. Or even worse, ALL THREE!.