What is the most affordable way to travel between cities in the south of France? For example Perpignan to Arles on May 16th. Is it recommendable to book tickets online? Or wait until you are at the actual stop to buy them in person?
Train is the most common way to connect those cities and train tickets offer advance-purchase discounts if you're ready to lock them in now. Compare prices at www.raileurope.com and www.capitainetrain.com. There is no deadline to buy, but the cheapest rates sell out first (and probably already have).