You can save Honor points, of course, until you reach level 80, even though everything at that stage will be much more expensive, and you won't be able to buy as much with what you earn today. Is this inflation enough to make you just wait till later to PvP in battlegrounds? Or do you want to hit 80 with us many points stored up as possible? Do any of the current PvP rewards look attractive enough for you to purchase them now instead of waiting?
The Arena is a somewhat simpler proposition. Any points you have will be gone as you start leveling up again, so you have to spend them now. Are they still worth earning? If so, will you spend them on gear? Or will you buy the special PvP gems in order to put them in gear you get later on?