Beijing - Haerbin flights are ridiculously cheap, as low as 380 Yuan one way, all in. I assume you checked expedia etc instead of ctrip. There's a thread with advice about how to book domestic flights.

Check out ctrip.com, but only around 4 to 8 weeks out for a good estimate for flight prices.

Going on two tickets means you need to have enough time between the flights in PEK to claim bags and check-in again. This can also involve changing terminals. However, all this is no big problem.

Another alternative is via Seoul. CZ and OZ (both not OW, though) have flights to Harbin, around 2,000 yuan round trip.

There's still no decent fast train to Harbin, altough the Beijing-Changchun-Harbin line is supposed to open in late 2011 and cut down travel time.

I would definetly use the miles to either PEK or ICN.


Edit: I assume her daughter is fit enough in Chinese and travelling in China, so why not suggest her to have her daughter pick your friend up in Beijing and show around the Chinese capital?