Hey, I live in Grenoble, also known as the (french) Alps' capital

lol
Most of the resorts which have been said before are considered expensive here. If you want a good snowparks, you have Les 2 Alpes, Avoriaz, Tignes, La Plagne, La Clusaz and Les 7 Laux.
The cheapest is Les 7 Laux and it's also a good place for easy (to hard) big mountain. It's not a very big resort but it's great.
I also ski in Les 2 Alpes which is more "newschool", I mean you'll see more freestylers from all over Europe. Great for all skill off-piste.
I haven't ski in Avoriaz but I know it has a great park, so do Tignes, la Clusaz and La Plagne but I think it's a little more expensive.
I think les 2 Alpes should be great for you, but try to get more informations about Avoriaz, Tignes and La Clusaz (Candide's, Loic CP's and Lolo Favre's home resort)
I put Les 2 Alpes over Les 7 Laux because it's more an "international" resort whereas Les 7 Laux is more a local resort.
Hope this helps you a little