Here are the list of hostels ranging from 500 to 3000 rs ( if you are not looking for shared spaces some hostels also provide individual rooms)
hostels in north
dream hostel- vagator
gostops hostel- vagator
happy panda hostel- arambol
paapi chulo- vagator
the hosteller- anjuna
hostels in old goa
old quarter by hostel crowd- panjim
white blanco- panjim
Hostels in south
the lost hostel - palolem
whopper hostel - palolem
bunk n brew- agonda
jungle hostel by strumfrie
There are few good hostels in North like vagator anjuna etc, can check will good as well as budget. it's season time in Goa so hotels etc have already increased their price
Today things most of the people prefer zostel and hostel , but they're some hostels which are mostly based on your budget weather it on any price range use hostel World site it well help you find the best suitable hostel according to your price