In Himachal you can opt for the following treks which are under your budget :-

Sar Pass trek, Hampta pass trek, Yulla kanda trek, Bhrigu lake trek, Kareri Lake trek, Kedartal trek, Rupin Pass trek, Kuari Pass trek

And in Uttarakhand you can go for Valley of Flowers trek, Nag Tibba trek, Chopta Chandrashila, Kedarkantha trek.

So these are some of the best treks under your budget .