When getting from place to place in India, the cheapest way is by train. It is how most people travel within the country and therefore someones best chance to meet people from India on the move. I shared a multi-layer sleeper cabin with five, got general admission once, and everything in between depending on availability. Along with the people, you get to see the countryside. Be forewarned that much of the time the toilet is just a hole going straight down to the tracks!