Every once in a while I check eBay for microscopes because a nice field (dissecting) scope would sure come in handy at times. So I came across this listing:
http://www.ebay.com/...872.m2749.l2649
50X - 500X was really more than I needed, but hey - $12 and change?! I got it today and here are my findings. FIrst off, this is not really usable as a field scope. It has a fixed focus, and you have to position the camera in order to get the object in focus, which requires a lot of patience. Second, the magnification is not adjustable, apart from using digital zoom in your photo editing software. Third, the objective must be so close to the specimen that there really isn't room to manipulate it, plus you would lose your focus anyway.
Now, having said all that, this thing is a lot of fun! Here's a photo I took of a dime just now:
Dime.jpg 206.1KB 0 downloads
Still looking for something that will serve in the field.