Don't forget that the Nokias that Speakout sells won't work outside N.America.
Well, the Nokia 5200 might.
You can probably get a monthly plan cellphone contract with Rogers/Telus/Bell, and that MAY work in China, but expect to pay through the nose. Make a lot of phone calls, and your bill will be higher than the price of your plane ticket.
One way that might be the easiest, would be to buy a cheap phone and phone service in China. Should be considerably cheaper to use.
Make sure the phone is quad band so you can sell it here, or use it yourself.