There're a couple of bros asking me abt HP & SIM card in China. There's already a good report on SIM card in China in ZHuhai Thread (which I greatly benefitted from), you can try search for it.
On SIM Card:
There're 2 mobile companies in China: China Mobile & China Unicom. Between them, they offer 3 major type of cards: local only, within Guangdong only, & nationwide card. Between these 6 combinations, there're way too many types of cards to choose from (some more ex but more stored value, some with more free off peak calls etc). I would recommend China Mobile since it much more established; ie better reception especially along highways when travelling between cities. Depending of what is your need, you can ask the shops & choose for yourself. Of course, Nationwide card charge more than the Guandong only card & local card, which makes sense. Generally for short time stayer, you should be able to get a pre-paid SIM card with RMB50 stored value for RMB50.
On made in China HP:
The HPs are really very cheap (& you need to bargain hard), but reliability was a big concern for me. Both mine & my bro's are still working fine after 3 weeks

. I would highly encourage ppl who often travel to buy the 2-SIM card HP (shuang ka shuang dai). Its ideal because you only need to bring 1 phone when overseas, & 2 SIM cards are functioning together (at the same time).
To save even more $$$, you can check out some of the call forwarding companies like sunpage (
www.sunpage.com.sg called budget roaming), which can forward all your Sgp HP calls to ur China number for only 28cents/min.