Depending upon what you want to probe, you may want something with a long working distance. That is, centimeters rather than millimeters between the lens and the probe. This can easily be accomplished, but not usually with the cheapest scopes or cameras.
One heads up on the dental type. I bought one of these a bit under $100 to try out. It didn't work out for me, because the eyepiece magnifications weren't individually adjustable. If you wear glasses and have more than a diopter difference in correction between your eyes, make sure they're individually adjustable. Not sure of what's out there, but the better (and more $$$) ones will have this.
Longest working distance (yet high power) stereo microscope I own is a "colposcope" retired from medical duty. Who knew? Even an ordinary stereo microscope, of good quality, should have a few inches of working distance at around 7-10x.
MattiJ's camera example seems to be one with a decent working distance -- maybe a couple inches. It's a spec you'll likely want to check.
The advantage of a low power stereo microscope, over the single tube of a camera, is preserving a better sense of 3D depth perception.