I have a Canon lide scanner (model 100, I think), which I purchased for about £30. I use it for scanning documents & photos and I am very happy with the results. The unit is USB powered and so does not need a separate power supply.
Unfortunately Canon no longer make the particular model – the lide 110 looks like the nearest thing available (but it is £50 – free postage). The two reviews posted are positive, so I would definitely consider it if I were in the market for a scanner.
http://www.ebuyer.com/product/236670