OK. What you probably need is an
unlocked GSM phone with all four bands, 900 & 1800 for China and 850 & 1900 for the US. It might be helpful if you got an Asian version for easy access to the common Chinese characters. It would probably also be handy if it were a "smartphone" that also had WiFi and could support
VOIP calling. From what you describe your needs being, you probably do not need a 3G phone. It's easy to find a phone that satisfies these requirements for under $150, except it's hard to be sure about easy access to Chinese characters. Maybe some others will have some advice.
At any rate, you could use this phone with a non-contract service while here in the US and then switch over to a Chinese carrier when you go there. There are also some options for keeping a US account active at very low cost.