which area do you prefer?
If you choose to live near airport, I think it's not so convenient to go to downtown.

How about those youth Hostels? If you want really cheap places?

Here is some information I found from previous threads on this forum:

Dongcheng district:

Peking Downtown backpackers Accommodation
Double: RMB 170/ day
Bike rent: RMB20/ day
Add: 85 Nanluogu Xiang, dong cheng district.
TELL: 010- 8400 2429

Zhao Long Int'l Youth Hostel
Double: RMN 160~300/ day
Add: 2 Gongti Beilu ( behind the Great Dragon hotel). chao yang district,
Tel:010-6597 2299 ext 6111

Youyi Youth Hostel
Double: 180
Add: 43 Sanlitun Houjie, chaoyang district
Tel: 010-6417 2632

The last two are close to Dongzhimen.

THere's also one on nan luo gu xiang, and one on jiu gu lou da jie, as well as many others.....so an internet search for beijing hostels. we can tell you if the location is good.

365 INN: RMB 50-60, 4-person rooms, book in online is available, go to: 365inn.com.cn

Drum tower youth hostel: RMB 50, Dorm room, 51 jiu gu lou da jie, xi cheng district.

Far east int'l youth hostel: RMB 45-60.70, 4/6/8-person rooms., 90 tie shu xie jie, xuan wu district.

Qianmen chang gong: RMB35/bed, 6-bed rooms, RMB40/bed, 3-4 person rooms, 11 ying tao xie jie, xuan wu district, cellphone: 13901123938

............etc

And all the information u can find on our new Insider's Guide to Beijing 2008

Just remember! Do not go to Red Lantern Hostel! The owner has some problem with his personality..

Try any of the JinJiang Inns. There are 16 in Beijing. Clean and safe. I use them all over China.
www.Jinjianginns.com
Prices are all around 20 Euros
Regards
Ralf