You can estimate the approximate budget needed for a trip to the city of festivals based on the cost of flights, accommodation, meals, and possible entertainment.
While plane tickets tend to get cheaper as summer approaches, the opposite happens with other travel expenses in Cannes.
From May to September, the city hosts film, advertising, television, and other festivals. During these events, the cost of hotel rooms rises significantly. If you are fine with staying in Cannes for 80–90 EUR per night during peak season in a small 2-star hotel such as Estérel, Albert 1er, or Florian, you will be warmly welcomed.
Just be sure to book your room in advance and keep in mind that during festival days you may be asked to pay for the entire duration of the event, even if you are staying only for one or two nights. Rates drop only in the off-season, as the days between festivals are called here.
The same applies to prices in restaurants and eateries. On non-festival days, set lunches (starter, main course, side dish, dessert, without wine) in budget restaurants and cafés cost around 25–35 EUR per person, while dinner is about twice as expensive. However, even a single portion here, according to numerous tourist reviews, is large enough for two.
To make a holiday for two in Cannes or with children really inexpensive, it is better to cook your own meals. There are plenty of grocery stores in the city, and in some of them you can even find familiar Eastern European products — varenyky, pelmeni, kvass, sour cream, cottage cheese, buckwheat, pickled cucumbers, and so on. All this is sold at low prices, attractive even to the French.
As for entertainment, in Cannes you can enjoy plenty of it, since access to many events is free. In June, you can take part in the Music Festival, and in July — the Fireworks Festival. Even some of the films screened during the May Film Festival are available to the general public free of charge.