Are there albino polar bears?

Yes, there are albino dogs, deer, birds, fish, gorillas, gators, sheep, rabbits, brown bears, etc. Several pictures at this site: http://verobears.blogspot.co.uk/2011/12/albino-polar-bear-cub-elvin.html?m=1
http://www.polarbearendangered.com/albino-polar-bear/

Albinos are people or animals that lack the normal pigmentation of skin, hair, eyes, of their race, genetics, species. Since the normal pigmentation of polar bears is white hair, the albino trait would apply to polar bears that have pink eyes with red pupils, pink nose instead of black.

Polar bears do not have white hair, they have transparent hair which looks white because of the light. They also have black skin.