Sex and the Single Ferret -- got a girl? Watch out -- when she goes into heat she WON'T come out by herself. In fact, she'll die without your help (or a male's). Fix her, breed her, or talk to your local ferret-service for weirder solutions (like breeding with a vastectomized male to take her out of heat without a pregnancy).
Got a boy? Sorry, this option isn't much better -- unneutered males smell worse and can be more aggressive, especially to other ferrets.
Face it -- pet ferrets need to make that visit to the vet, and EARLY! unless you're willing to cope with the consequences.