This won't work, because it requires the user to build a mental budget each time they go online. That is the exact opposite of how internet use has worked since

This won't work, because it requires the user to build a mental budget each time they go online. That is the exact opposite of how internet use has worked since its inception. Secondly, if there really was a big opportunity in enabling micro transactions, the main players (PayPal, Visa, etc) would already have some offering available after ~25 years of paying for stuff online.