Personally I'd love a six-pack of Christmas ales. I wouldn't be able to pin-point where to buy all of these but I bet the better liquor stores would have most of them. But some of these may be hard to find in the single bottle racks, since they're seasonal. These are a little more expensive than your typical lite, but it will probably still add up to be less than a decent bottle of wine.
Anchor Steam Christmas Ale - the distinctive tree on the label changes each year, as does the recipe. My favorite. If you have to buy a whole 6, I'll let you know where to drop off the other five.
Abita Christmas Ale, may be a little harder to find, also changes from year to year.
Sierra Nevada Celebration Ale, fairly easy to find.
Great Lakes Brewing from Cleveland makes a heavily spiced Christmas Ale with honey, fresh ginger and cinnamon.
Goose Island Christmas Ale. Better on tap at the brewery, but still a nice warmer.
Tröegs Mad Elf Holiday Ale, from Harrisburg PA
Other non-denominational, but seasonal choices might be:
Berghoff's Hazelnut Winter
Young's Winter Warmer
Pete's Wicked Winter Brew
Samuel Adams Holiday Porter
If you were truely her friend you'd forgo the 6-pack format and give her a few bigger bottles of great beer like Affligem Noël or Corsendonk Christmas Ale.