As long as a ferret cage is fairly sturdy, then this is no reason to get an expensive cage. However be aware that animals like ferrets, rabbits and even guinea pigs need room to be healthy. So if a cage is sturdy, but has a cheap price solely because of its size, you may not be giving your pet a very good living environment. Opt for a bigger cage.
Medium Sized Ferret Cage:
Medium Sized Ferret Cage pictured: New Medium 3 Levels Ferret Chinchilla Sugar Glider Cage 24″Length x 16″Depth x 24″Height *White* by Mcage