Whilst looking for slingbox prices, i found a £31 dixons code on this very forum.
I decided to apply it, and it comes up as a £50 discount rather than a £35 discount, making the slingbox £129.99 + £4.99 delivery. A true bargain!
Maybe quidco aswell? (i'm not a user)
I haven't gone through and ordered yet, so not sure if it will get cancelled, but still worth a try!