Most of the ferrets you find in pet stores will be sables, albinos, white with black markings, champanes (spelling), and dark sables. You will also get bibbed, mitts, and blazed. There are not many "rare" colors or markings, unless you get them from a breeder.
If you are considering getting a ferret, please consider getting two. They do best in pairs or groups. Also, check out this forum. They are great and focus on natural care and feeding. PM me if you have any questions.