Offer is same as PC World as they are part of the DSG company. Dixons and Currys has no 10% discount code though, but if you prefer the turqoise edition it's available for just under £4.
I bought the grey edition from PC World and they perform nicely. I wouldn't pay more than £10 for them though. Sound quality is average but for £3.57 I can't argue. I compare these to my integrated speakers in the monitor and the Saitek Expressions are indeed more powerful. Just make sure you don't pump the volume too loud otherwise they rumble and becomes distorted.