Yeah you can get an old Bauch&Lomb for under $200. Probably need an LED illuminator ring for $10 too.
They have great field of view (cm) at decent/variable magnification (20-100x) and response time is instant, whereas your phone/USB are going to have just enough delay to be annoying.
They have great field of view (cm) at decent/variable magnification (20-100x) and response time is instant, whereas your phone/USB are going to have just enough delay to be annoying.