Blockbuster are selling the Family Guy Season 6 DVD boxset at £17.96 until 21st October, while stocks last.
I'm assuming it's instore, because I can't find it online.
I know that Amazon are selling it for £17.98, and add £0.29 for delivery = £18.27. So that might be preferred by some people to get it delivered. But if you pass a Blockbuster you can save a few pennies :)