How would you go about

I’ve been trying to convince my wife that getting a beaded dragon would make an awesome pet for the family. (Yes I know dogs are better but my living situation kinda sucks for getting a dog) I have a 3 year old daughter and I want something that would be happy with her handling it (under supervision of course) I’ve just been trying to justify the purchase for a 40 gallon (yes I know it would eventually need something bigger) with all the stuff you would need is around 175-200$. Her argument is space for the enclosure and she flat out does not think they make great pet.