These are perfectly fine...not exactly a tone of technology involved. I have several of these (bought a 5 pack) and the higher end Gruv Gear ones - I can't see any significant difference.
I sent one to Bassfan when he posted a wanted ad - cheap enough to give away - I'm sure he'd say they're worth £3.
I ordered three...expect to see one or more in the raffle at your nearest Bass Bash.