The price of 3G/3.5G modem and data plan are dropping. The minimum monthly service charge is $98-HK ($1-US = $7.8-HK) and the maximum charge is $188-HK for unlimited usage. The 3G modem is free of charge, surprise? However, you need to sign a contract from 18 to 24 months.
I bought a 3G wireless router, Edimax 3G-6200Wg, for sharing my 3.5G modem (Huawei E180). The turbo mode can increase the strength of wireless signal a lot although it is a IEEE 802.11 b/g router.
I tested it with Lenovo ThinkPad X61 and X200 as well as some other wireless network interfaces. When the router is enabled the function of WMM, X61 and X200 cannot associated with the router via Ubuntu 8.10 and 9.04. When it is disabled, all ThinkPads connected to the router flawlessly. Later learned that it is the bug of the Intel wireless card Linux driver/firmware. The bug has been reported to Intel.
In addition, you can use Huawei 3G modem flawlessly in Ubuntu 9.04 with a little bit of setting at the Network Manager.
By the way, I provide the APN of Hong Kong 3G data plan providers here for your quick reference.
3 HK : ipc.three.com.hk or mobile.three.com.hk (for some data card)
Smartone : internet
PCCW : pccw
CSL : HKCSL