$90 isn't bad, I paid $200 for one that steeps the tea as well.

It costs that much because I'd rather pay $200 than spend my weekend making a kettle (producer surplus). Next thing you know someone will be wondering why drinks cost $10 for $1-2 worth of ingredients.

If you want to save money just use a pot and boil the water in that, it's not like you really need a purpose built device for boiling water.