Dick Smith's Hobart store has 40-50 Telstra Turbo USB MF626S prepaid Mobile Broadband modems clearing for only $5. The old SIMs have been replaced so they're now on sale with a new SIM but NO DATA.
Saw this today when browsing for laptops at the Bundall, Gold Coast store in QLD. Vodafone K3771 USB Modem $19.95 with 3GB data. I checked and Vodafone stores were still selling this at $49.00
Bought one from Sydney south post office. $9.95 for optus prepaid huawei E160e usb modem with starter sim. Sim pack expired on 01/07/2011 already. But still a good deal for an USB modem.
This is the cheapest a USB 3G modem has been ever IIRC. It's locked to Boost, but can be easily unlocked. It is the Huawei E160E, which goes up to 3.6Mb/s. It is not usable on Telstra 850Mhz NEXT-G.
From the 23rd of december 3 mobile prepaid modem were reduced to $79 from $99 and include 200mb with the starter pack. The E1756 is the best of them as it supports speeds of up to 7.2mbps