The Swiss vignette is CHF 40. You can buy it at the border crossing.

If renting in France, be sure to ask if winter tyres and snow chains (if needed) are included. They usually are on the Swiss side ...it's that natural caution and preparedness y'know. Often not included on the French side, and you must** have winter tyres in Switzerland if driving in adverse conditions (cold, snow).

If the winter tyres are not included, it's often cheaper to pre-book. But it's also not uncommon for the car hire place to run out of winter-booted cars if they don't do them as standard....



** OK, it's not a law. But if you have an accident and do not have winter tyres, your insurance can refuse to pay up.