Paris to Bordeaux?

There is no long distance bus service in France, only regional and local buses. There are no budget airlines that fly Paris-Bordeaux.

Take the train. Direct TGVs make the trip in just over three hours (faster than flying when you factor in the time getting to and from airports, going through security, etc.). The regular 2nd class fare is 65.10 EUR. PREM'S (discount) fares, when available, are as low as 25 EUR. You can book up to 90 days in advance at www.sncf.com. Click on the British flag in the lower left-hand corner to view the site in English. To have the best chance of getting a PREM'S fare, book as soon as the 90-day window opens. Leave France as the default country, do NOT choose cancellation insurance, and print your own ticket. If you have to buy a regular fare ticket, choose the option of picking it up at the station or a ticket boutique.