The only time I would suggest a more expensive cable would be for a long run. Other than that, as I said, it's digital, either it works or it doesn't. If it doesn't work you will see artifacts on the screen, like when theres a storm and your Sky/Freeview/etc. goes down.
Gold plated connectors only have any effect on an analogue connection which can degrade, ie. scart.
Digital only degrades over extremely long distances, to the point where the receiver can not tell the difference between a 1 and a 0 (binary), for example digital television and this would certainly not happen over a HDMI cable.
In short, its crap, don't buy into it. There is no difference in picture quality, either noticeable or not noticeable.
£20? Try £4
http://www.ebuyer.com/product/130508 (Yes I know thats gold plated, but that was the cheapest).