I'm not sure how much of a "bargain" this is but Sainsbury's are doing two 600 ml bottles of Brewdog Punk IPA for £4.00.
I plumped for the last three bottles of Ridgeway Brewery bottle conditioned Bad King John (6%) for a fiver instead.
This was in the Loughton branch in Essex.
I agree with you Ale and Hearty about the Bateman's on price only as I've not tried it, but would point out that Tesco do four McEwan's Champions for six quid. The Old Tom at 2 for £3.00 in ASDA is also worth a look as Tesco seem to have stopped stocking it.