Let's see....
Wild Shape is gained at 5th level, when most casters get 3rd-level spells. That's a good basis to begin with.
A winter wolf is a Large magical beastie with 6 HD. It's slightly tougher than a Dire Wolf and deals cold damage with its bite. It also has the cold subtype and has a minor breath weapon.
Druids can turn into Large animals at 8th level, but a winter wolf is better than a Dire wolf, so I'd move it up to the equivalent of a 12th-level Wild Shape.
It's a shorter duration, but it is a (specific) creature not normally allowed.
3 (level) x12 (caster level) /5 (1/day) x 2,000 (command word item) x 1 (item in correct affinity slot)= 14,400gp
For the ability to turn into a winter wolf once per day for 2 hours (120 minutes = 12x 10/level)
You might reduce the price a little, since it's a single form, but I think the price is fair enough. You might add in a small bit of cold resistance (5) and/or the ability to ignore cold weather effects when wearing the cloak.