I realize this, but I still don't want to spend CNY in China. One of my Beijing bar buddies lives in Hanoi and invited me to visit her.

Incidentally, Ctrip called me back and informed me that they can't sell tickets to Hanoi, and even if they could, that the trains are sold out on Wednesday, so it looks like I'll be taking a bus.

ETA: I just grabbed a train ticket to Fangchenggang on D8251 via Ctrip (they charged me an extra Y20 this time and I didn't bother to figure a workaround because it was still really cheap). Remarkably, it's only a 1.25 hour train ride (v. 4 hours to Pingxiang). I don't have an exact plan on how to get from there to Hanoi yet, but I'm figuring that will entail two bus rides.