alt Hacker Newsit's very expensive though. i used to live in philly close to 30th and had a reason to go up to nyc regularly close to penn, essentially perfect for taking amtrak, but ended up taking boltbus just because the price difference was very significant and time wise it was only like 30-45min slower.
Pro tip for those who like risk and are traveling regularly for non timely purposes they have dynamic pricing that rewards literal last 5m. I do Amtrak for like $15-40 NYC-PHL. You have to be signed in to the app otherwise they won't give you the sweetheart deal. Refresh reguarly the price changes constantly in the last 3-4h though I'll typically rock up to Penn and buy one 10m before.