I hate the pocket microscopes. The edges are blurry, the viewing angle is tiny, and it's really hard to hold them steady. If your in a pinch they work, but IMO, it's better to invest in either a really nice 10x jeweler's loupe for $35 or buy a 200x digital USB microscope for $80.
The digital not only lets you see them on a big screen, but you can take photos, so you can really take your time inspecting your material. The loupe should be a quality triplex loupe, meaning it has three separate lenses bonded together so the image remains crystal clear. You place them over your eye and bring the nug to your face. You only need 10x because the design of the loupe allows you to bring it closer or farther away, without losing distortion. So in realty a good quality 10x should rival a cheap 30x-60x pocket scope. Plus the better loupes are color corrected, so you can be confident that your seeing clear vs cloudy vs amber.