I persuaded my parents who were reluctant to get me a snake initially as a 9 year old kid using logic. This included the fact that food costs would be lower than for many other pets and happened weekly over daily and that snakes only need a full vivarium cleaning every month or two months with spot cleaning. I also even pointed out the financial side of things by observing the initial outlay was higher and would work out as lower over the first year or two than a dog or cat considering the vaccinations as well as avoiding the need for a replacement over a longer timespan than many dogs.

The fact that mammals as pets typically need more maintenance than a snake does and thus even if I went away to university and had to leave the pet behind they wouldn't have to do too much actually really helped.

I would suggest working out how much a snake costs and the amount of care required for 5 years and then do the same for various other animals including cats, dogs, hamsters and gerbils. At least this way you can say look I have researched this properly. If you create a diagram showing this it will most likely have an impact.