The people living in the building are all fixed-line broadband. Go to Unicom Hall in the north of the post office. The cheapest seems to be 60 yuan/month (probably), including telephone charges.
The fixed line of Fangping Netcom is not easy to connect, so now I use the wireless network card of Telecom, 600 yuan/half a year /750 hours, which is a bit uneconomical.