when will the next sale go on?

Hi, I have been playing the sims for over 3 years now and I really would like some extension packs but I don't want to pay £35 because I'm 15 and I don't have much money. I don't like it because I would be spending more money on this extension pack then the actual game. I would really like the city living and the pets pack but I'm not prepared to spend £70 on them. I would like to know when the next sale is because I will purchase it when the next sale comes. Please can you tell me when the next sale will be. Thank you.