Well, something like this might be your best bet then:
http://cgi.ebay.com/20X-40X-Stereo-...ltDomain_0?hash=item5d28647ec4#ht_6236wt_1167
You can't do any back-lit cell work, but that not really what you are looking for with a dissecting scope.
I've never used an Amscope so I have no clue what their optics are like, but this one gives you decent magnification and a camera. If you need more or less magnification later, you could change out the 10x eyepieces for 1x, 5x, or 20x (so then your total magnification range would be 2x-4x, 10x-20x, or 40x-80x), which would give you a really respectable range of magnifications.
Like I say, I've never used one of their scopes. Most of the lower-priced scopes are really pretty decent these days, though, and to get nice glass (Zeiss, Nikon, Olympus, etc.) the price goes very high, very quickly.
BTW, expect that the scope will be under-lit. I wound up buying a separate lighting package and that makes a _huge_ difference. But you could easily make up some supplemental lighting with some super-bright LEDs. Heck, I used an LED flashlight as a supplement for quite a while. But you really have to expect that you'll supplement the light with something eventually. These manufacturers save money by putting in cheap lights.