India is damn cheap! While not quite as budget friendly as it used to be, there are plenty of backpacker hostels to choose from as well as tons of cheap guesthouses. The street food is plentiful and costs pennies, and if you don't mind being uncomfortable, even long distance transport will only set you back a few dollars. In short, it's definitely possible to visit India for $500 a month, or less if you're really ready to rough it.