You could probably pick up a SKY+ for less than £199 but there is no guarantee it would come with a Quad LNB so you would have to buy that then find someone to install it for less than the £1 SKY charge new subscribers

All things considered the SKY deals are pretty good.
I would not be surprised if at some point after Amstrad launch their SKY+ there is not another review of the prices but as yet there has been no official launch date announced.