Paretns won't let me get a ferret :( HELP!?

ok so me and my (younger) sister always wanted a ferret and bieleve me we have done everything to try and convice my dad and step mom to get us 1. my sister and i have done EXTENDED amounts of research we have both become ferret experts practicley! we both want a ferret in the worst way possible. we always try to go to the pet stores just to LOOK at them! we both raised over 240 dollers to buy supplies. but my parents said "not right now" (what ever that means). my step mom is worried about the smell but my dad rlly doesnt care he said its up tp my step mom but she nvr rlly gives us a striaght answer when we ask her. Me and my sis love animals so much but for some reason we are both drawn to ferrets. WE BOTH WANT ONE SOSOSO BADDLY! any ideas to convince my step mom into getting us 1??!?!?!?!?!?!?