Let your model grow a pair

Do you OOP? Everything has to be an object. But creating a `Money` class could be premature optimization. Premature Modelling optimization. You are not sending  spaceship to land on Mars. You can always enhance your model. Just use an `int` now. You'll be much more proficient. When you start using other currencies, or when you start having many different measures, you can grow your model up.

Write a whole working MVP, then evolve.