Hello! I've been lurking for some time and have managed to glean a great deal of useful information from this forum (thank you all for that). My husband and I leave on Tuesday and there are just a couple loose ends. We have decided that the RoissyBus is the most logical alternative to get us from CDG to near our home base (a studio near Place du Marche Saint-Honore). I've searched this forum and the metro website but can't seem to find details re: how to get tickets. Do we purchase them in advance or can they be bought right on the bus? Thanks so much!