Prices in Monaco in Supermarkets are the same like in France.
Uber doesnt work in Monaco.
In touristic places coffee is expensive (like in Cafe de Paris Casino Square), more than 7 EUR, like any other snacks and desserts.
Try to use airbnb in Monaco to rent an apartment for a few days. Or even stay in port of Cap D' Ail. You will never see the difference or even the border between Port of Cap d'Ail and Monaco (Fontvieille area).