I only ever use Bosch batteries for my own car and I've found they are cheapest from Vauxhall dealerships with the discount we get - so find someone you know that gets one too

Never had any problems with the cheapo batteries from places like Eurocarparts except on bmws [an autoelectrician explained to me why but he's a 60 year old white jamaican with the full on accent and after 2 minutes of him talking I zone out and start thinking about that film Cool Runnings ].