I am very sad to hear this. Unfortunately, adrenal disease is surprisingly common in ferrets. I work at an urban veterinary clinic and I cannot tell you how many times we see ferrets (of all ages) come in at varying stages. Do you know which form of adrenal disease Ricky has? (Malignant tumor, benign tumors, hyperplasia). Do you know how old he is?
Generally the vet has two ways of approaching this. One is obviously the surgical route. This might involve taking one of the glands, then taking the other 1-2 months later after the ferrets body has had time to start producing hormones on its own. This is the most encouraged route simply because it is honestly the most successful. Over 90% of ferrets who have this done never see a reoccurrence of adrenal issues, and are healthy as soon as they heal. A rough estimate I saw said over 80% of the time the ferret can be cured just be having the left adrenal gland removed.
The other option is medication. I think currently the most commonly used medication to treat this issue is Lysodren. If the vet administers this, and it works, there will be no need for surgery. This effectively destroys some of the adrenal tissue and promotes healthy new growth. However, this medication will be something the ferret will need for the rest of its life- and so expense wise it will be roughly about the same. There's also the chance this medication will not work for some animals. So it's a good idea to discuss both options heartily with the primary vet.
Either way, it does look like funds for this will be high. Ferrets are expensive pets, and taking care of a life-threatening issue such as this is expensive. However, talk to the vet about this! Most vets are very understanding about realistic costs to their clients, and can come up with affordable plans so that the client doesn't have to pay all at once.
Best of luck to little Ricky!