I want them available during the year, not just the winter holidays.
Cranberries last well in the freezer. Although you can freeze them in the plastic bag, I'd recommend putting them in a stronger plastic bag or container. (I learned the hard way - I didn't last year, and during a power outage, my cranberries defrosted and leaked red juice all over my freezer. Ugh!) I've also frozen cranberry sauce - that works fine too.
I've kept cranberries in the freezer for about 6-9 months, and they still taste just fine. You can place them in a resealable freezer bag and take out as many as needed each time - most recipes call for fresh or frozen cranberries, just like with blueberries. You may get a little freezer burn on some of the berries, but in baked items or in a sauce, that's not typically a problem. So go ahead and stock up!
I've hoarded cranberries to the point that I use up last years stash to make way for this years. They're ideal for freezing in a bag, just unzip count out your required amount of cranberries & pop the bag back!