When travelling on the “Autoroutes” (motorways) toll charges are often a necessary evil as the country is so huge in comparison to England, Ireland Scotland or Wales.
If you are planning to drive 400-500 km then avoiding the Autoroutes would just take forever. The Autoroutes are marked "A", for example “A71”. ("N" roads are trunk roads, and “D” everything else). Read this if you want to learn more about French Road Signs.
I’m loathe to put prices in this FAQ post as they are always subject to change and I don’t want it to become out of date. Therefore for you to calculate exactly how much it will cost in toll charges I have put a couple of links at the bottom of this article so you can visit a website that offers a “toll road calculator” and a "toll road map".
The reason there are so many toll roads in France is simply because unlike the UK the main roads are not owned by the government they are operated by different companies. The number and variety of the toll operators does mean that there is little consistency over pricing.
Some of the toll roads are terrific value and can save you a couple of hours on your journey time and it’s worthwhile remembering that in Brittany the government do own the roads so there are no tolls there.
Unfortunately, some toll charges are very expensive so we suggest you read this also.