New snowboard this year, any suggestion?

I'm 5-4 i weigh 125. Im looking to start riding more park, but I need a board that can still ride all mountain. I could probably spend 400$ on the board alone. Also, what size should i buy if I am looking to grow into it, I imagine I will be 5-8 or so, so should I just get a new board next year or buy it big?