A Magnum of champagne

whizzing

I want a double size bottle of champagne for a present. Where would I get this cheapest !!! They seem hard to find.:beer:

gastronomix

Depends which one you want. If you want a well known name brand, Moet, Veuve, Laurent Perrier etc they will be more expensive than a lesser known house or supermarket own label.
Try looking at supermarkets websites or Oddbins, Threshers etc. Smaller stores may not carry these as regular stock but possibly be able to get them in for you. Plenty of online wine merchants who will send them out for you.
Generally cheap Champagne is in my opinion best avoided as it often lacks bottle age and any flavour complexity. The equivalent spent on sparkling wine can get you a better beverage.