This city is full of hostels, hippy & very affordable.
Some of the nice hostels here are Hipostel, Zostel, The Wayfarers, The Hosteller. Prices for most of the hostels here are really cheap & would usually cost around 250-400 per head per night.
On the travelling front, make sure you do the famous river rafting here, river rafting cost 500 bucks per head for a good 2hr 30mins 16kms stretch & 250 per head for a 8 people raft (total 2k) for GoPro recording of the rafting.
If your trip is well planned in advanced, then try the Bungee jumping which requires around 7 days of advance booking & it will cost around 3800 INR, but it's worth every penny.
One day you can dedicate to trying out numerous book cafes & other cafes here in the city. Don't miss out on Beatles cafe.