Need advice to convince parents RE ferret. ?

For awhile I was admiring ferrets and today, that I went to pick up a few silkeies for my lizards and I saw that they got a huge shipment of ferrets adorable baby. I played with them for like, 20 minutes to what my friends dragged me out of the store.

I know how much responsibility it is to have a pet. The cost of vaccinations, castration/cats/descenting.
I know they are prone to diseases and I have an "Emergency Fund" to my current animals.
I understand the need for ferrets from the time of the cage and the exersize. I could leave the ferret Park every day, I am with my dog, which extends from s.
I have a dog, a cat, a gecko Leopard 2 bearded dragons and tarpaulins ears red beam, Hein?
Yah, but I want something... care. I love my lizards and spend a lot of time for them.

My point is, how can I I convince, they have no address financial situation, let me keep a ferret when they believe that the House is a ZOO! Please do not publish if you want to discourage me, THX!