In the 2010 France book the surface transportation budget for a 3 week tour of France is $750 per person. In the 2014 book it says the cost is the same. Is that a true statement?
I would guess the amount you spend would be determined by where you are going and how you are getting there. If you would provide an itinerary and your method of travel (car, train, etc.) it would be more helpful. How many people will be with you?
The biggest factor would be the Dollar/Euro exchange rate at the time of publishing. In the last 5 years it has varied from 1.5 to 1.2 Dollars to buy a Euro. The average is 1.35, and that is what it was in April 2010, and about what it is now. But as you can see, it can vary up or down by 10 to 12 % over the course of time. Rail tickets purchased in advance may have even dropped, but I know Paris transport costs (in Euro terms) have increased in the last 4 years, but I don't think more than 10 %.