i had one some years ago, it was absolutely no good at all for inspecting fungi spores with, as the magnification was nowhere near good enough,
i think you need a microscope with a x 400 or even x 1000 magnification and oil immersion (A.F.A.I.K) those little usb hand held ones come nowhere close to that kind of specification

so while cheap they would not be at all suitable in my view Mary.
i cant really advise you on any particular microscope myself, but a search on the web should provide you with lots more info if you are considering the purchase of one for yourself,