On a budget, weigh it — Cannes isn't cheap for what it is.
Train ~€7 each way; spending high
Strut the Croisette past palatial hotels and designer flagships, see the red-carpet Palais des Festivals, then escape uphill to the genuinely charming old quarter of Le Suquet for the view. The honest read: outside festival season it can feel like an expensive shopping strip, and the famous beaches are mostly carved into paid private clubs.