Last one I bought was from a scrappy... If you've got a good one near you they'll have a stack of them and will let you choose (offering guidance on size / specs if required). I was just looking for something as big as I could get away with on the tray of my mrs' 8L. Ended up with a rather spanking Exide one, sealed maintenance-free job which could not have been any more than a few months old. I think it cost £20 plus a Vodka and Tonic for the Treasury; it's never missed a beat.
Come to think of it, the one I had before that was from a scrappy too - I went in and asked for the biggest meanest thing they had - got a mahoosive one to go on my old B5 (Diesel with Aircon), again for between £20 and £30; and still going strong a couple of years later...
Of course you might be dead-set on brand new, but I thought it worth a mention...
Regards,
Rob.