Updated 15 December 2014.
Don’t know if it’s the exchange rate, but there seems to be less than last year. Seijo Ishii (top) has a slight discount on Xmas pudding and mince pies and so is currently the cheapest for those things. However, not all locations have them.
Seijo Ishii, many locations often inside station buildings, e.g. Gotanda station building and inside Shinjuku JR (actually inside the station, near platform one)
Walkers Xmas pudding 451g 1394 yen
Walkers Xmas pudding 227g 1070 yen
9 Walker’s mince pies 854 yen
However, the same shop in Oimachi seemed to have nothing!
Queen’s Isetan, a few locations including inside Shinagawa Station
9 Walker’s mince pies 890 yen
Walker’s Xmas pudding 227g 1180 yen
Kinokuniya, a few locations including Kunitachi
Xmas shaped shortbread
Nissin, Azabu Juban
Robertson’s Mincemeat jar 972 yen
fresh brussel sprouts 680 yen
frozen brussel sprouts 823 yen
tiny Walkers Xmas pudding 594 yen
Meiji-ya (various locations including in the basement on Marunouchi Building – commonly known as Maru Biru – opposite Tokyo Station)
9 Walkers mince tarts 227 gram 972 yen
Walkers Xmas pudding 1296 yen
Walkers rich fruit cake
Yamaya, many places including near Hamamatscho Station
French Cake aux fruits, probably suitable for icing to make a reasonable Xmas cake (or at least that is my plan) 600 yen
Kaldi Coffee House (many locations, often in or near stations)
Just Walkers Xmas-shaped shortbread (which doesn’t seem especially Xmasy to me!) and the same cake as Yamaya
National Azabu, Hiroo
good roast chickens, plus more stuff I’m sure – hope to get there on Monday
Aeon (many locations, including Shinagawa Seaside)
very reasonable whole roast chickens
more info on those various locations elsewhere on this blog. Any more finds in comments please!