Just bought the JJC version of this, and it makes so much more sense (at less than a tenner!). Injection moulded products like this cost less than a £1 to produce (depending on where it's manufactured), so a £30 mark up on the Canon one is pushing things a tad.
Have checked the JJC for moulding/manufacturing faults & the finish is pristine & defect free (very high quality!)
Hey if your pro/semi-pro or value for money isn't an issue, then you'll obviously feel you have to choose the Canon option. But the 20 quid I saved on this has gone towards a Hoya Pro ND-8 filter for my 10-22mm, so it's worth bearing in mind if you've already splashed out a substantial amount on a 10-22mm lens or similar (which should have had a lens hood bundled with it in the first place).