I'm totally serious - reptiles are the way to go for kids' pets.
They like being played with for the average kid's attention span in exchange for some warmth. They don't care if no one plays with them for the rest of their life, as long as they have heat and food. Cornsnakes don't bite. I don't think geckos etc even have teeth. Hamster bites hurt. Rabbits, we have established, can be a Lot Of Bother.
The best pet we have (and, we've investigated this quite sicientifically) is the snake. Every month it does something interesting, like sheds it's skin. And, it eats once a week. And, it's bum stays put. And, it has no toes to break. It's totally silent, no fur, needs cleaning out once every 6 weeks if you pick out the poo (ok, that's bogging) and, it has cool factor "oh, you've got a puppy? Well, i've got a snake, sucker" . ANd, as long as you give it a heat pad and a defrosted mouse once a week, it's totally happy. And, you can build it hidey holes out of lego and loo rolls. And, your pals think you are totally cool. And, when they come round they help make mazes for the snake to explore which keeps the playdate quiet for hours.
Cornsnakes get abandoned all the time, so you can pick them up from the RSPCA for cheap as chips - and, they'll even give you one that's easy to handle and feeds/poos/sheds without any bother. --plus, that means you can get one that's already fairly elderly. Life expectancy is up to 20 years for a cornsnake. Get an old one)
Costs the heat pad to run (cheaper than a bearded dragon/tortoise who need basking lamps at mega-wattage) and a mouse costs about 90p, one a week.
However, keep it away from your baby budgie.