Are rats an expensive pet?

Are rats really an expensive pet to own? I've heard that they can be quite low-maintenance and cost-effective compared to other pets like dogs or cats. But then I've also heard that their specialized food, cages, and toys can add up over time. So, are rats truly a budget-friendly pet option, or should I be prepared to shell out quite a bit of money for their care? I'm curious to know if owning rats is as cost-effective as I've been told, or if there are hidden expenses that I should be aware of.