If you are looking for portable duplex scanner, you can check out the ScanShell 3000DN from ScanShell Store. The ScanShell 3000DN is only $319 with 30 days money back guaranty and with free technical support.
This duplex scanner is very small and light making it a real portable duplex scanner. The weight is only about half kilogram. The length is slightly wider than the A4 paper at 300mm. Its width is only 50mm and height at 45mm.
But don’t be fooled by its small foot print. This little genie has a resolution of 600 dpi x 1200 dpi. That is as good as the monster scanner you can find in your office. It can scan A4 or Legal size paper with super fast speed at 3 pages per minutes in color and 6 pages per minute in black and white.
It consumed so little power thus it does not require any power adapter to function. It only requires USB connection for its power supply and also for the data transfer. That is why this duplex scanner is very portable, no more tangling power cable and adapter to carry around. Just plug it into your notebook USB port, no need to look for power socket.