Here is a picture of my low power zoom microscope, which I can highly recommend. It has a variable zoom from 10x-40x, which can be changed to 40x-160x by changing the lenses. It is very easy to work under the lens, as the picture is not inverted and there is a lot of free high under the lens. I primary use it when I have to solder PBCs, but I am also using it for other purposes.
The microscope is brought on Ebay, which is my favorite shopping site. The actual model is not important as the data are similar - mine is called Müller and bought in Germany.
Here are some pictures of the same PCB, but in different magnifications. (x1, x10, x40 and x80)
The pictures are taken by holding a digital camera to the lens!