Where to buy whiskey in Hokkaido?

I'm going to Hokkaido this October and I'm looking to buy single malt and blended whiskeys home for souvenir.

Any tips where I can buy?

Also, any idea how much these cost?

Yamazaki
Yamazaki 12
Yamazaki 18
Yamazaki 25

Thank you.

If you're going to Hokkaido, why not go to the Nikka distillery: http://www.nikka.com/eng/distilleries/ ?

For the Yamazaki, you'll find the youngest of them are sold widely in combinis all over Japan. Different brands of combini sell different distilleries' whisky, and they tend to sell them in small bottles (maybe 35cl, or maybe 20cl - I can't remember), so you can build up quite a collection.

I'm sure someone else (or your hotel) will point you to a more specialist shop in Sapporo to get hold of the older stuff.