Cheapest way to get to NYC?

Hello people. With the Megabus route from DC to NYC now discontinued, I'm looking for the most affordable way to make the trip. I visit my family in NYC every few months, and with Megabus being $15 round trip, it was a great deal. Other options like Amtrak are around $60, and most other bus services aren't much cheaper.

Can anyone suggest the cheapest way to travel from DC to NYC? I'm not concerned about comfort, just finding the most budget-friendly option.