This was basically the same math you see in business administration classes. It's nerd math if you're talking electronics. I can rent a modem from the cable company for $8 a month with free upgrades as needed or I can buy an $80 modem for myself every few years. If I can use my own modem for more than 10 months, then I've already come out ahead. So this woman would need to sacrifice a $5 of her budget somewhere every week for a year. That's often optimistic fantasy that I think gets a lot of debtors in trouble.
It's so weird being reminded of that other world that exists alongside reality, where the number of times people assume they'll wear an article of clothing or piece of jewelry is in the tens