I have done an absurd amount of research into buying a scope. If you are patient, you
will find a good deal. Also, consider that if you are going with a serious scope consider looking into a "trinocular" scope, which has a third eyepiece to attach photography/video gear to.
I ultimately went with a Nikon SMZ-2T which is a
stereoscope- you don't need to prepare slides, you can just put an object under the tubes and focus.
A good scope will hold a lot of its value. Brand new it was $7000, going out of business liquidations happen A LOT on this stuff and got in at auction for under $500.
"If you need help choosing a scope:
https://amscope.com/pages/how-to-choose-microscope
This guy on a forum made some good points, except I disagree about "brand doesn't matter." It does- you want something proven with parts available.
Brand and model are irrelevant. You need a compound microscope with:
a. condenser (very low cost microscopes do not have them but it is recommended)
b. objectives 4x, 10x, 40x, (100x oil objective is expensive and not needed unless special purpose)
c. 10x eyepieces
d. mechanical stage recommended and not only stage clips
e. coarse and fine focus knobs
f. DIN 160mm ISO standard
pretty much all entry level microscopes have these (and also advanced)
Do not buy microscopes that:
a. only have one focus knob (you need coarse and fine focus)
b. have plastic objectives (toy microscopes)
c. have non DIN objectives (possibly toy microscopes)
d. have a built in camera (toy)
e. are historical (put them into museum)
f. are special purpose (inverted microscopes for cell culture, polarization for geology etc.)
g. do not buy used, unless it is over a shop, which did servicing.
in my view irrelevant:
a. halogen vs led
b. unrealistically high magnification (2000x) no image information gained and possibly marketing measure.
preferred, if money available,
a. trinocular head (for photography)
b. otherwise binocular
c. koehler illumination for photography
d. large and heavy for stability
e. wide field eyepieces"
Think of it as you would a scope or a good pair of binoculars.