A few years ago, in June 2010, I ordered a USB Microscope (DigiMicro 200X Zooming USB Digital Microscope). I chose this particular model because it worked well with Linux.
My son (Matthias) and I gathered some wild flowers from a nearby mountain, and then used the USB Microscope to take these pictures.
The snapshots were taken using “Cheese” (a webcam program). The image size was 1280×1024. We then adjusted the colors in Gimp. This was necessary because the originals had a definite color cast to them.
In Gimp, I think we used mainly the White Balance, Normalize and Stretch Contrast options under the Colors->Auto menu. Also under the Colors menu in Gimp, Hue-Saturation is helpful. Pick the color (Red or Magenta usually) that is too strong and tweak it down a bit.
For a $40 device, we thought the pictures were fairly decent. You can decide for yourself! Click on one of the pictures to enter slideshow mode: