Should I buy a more expensive microscope first, or should I buy a cheap one and then a better one later?
Some people say that one should invest a little bit more at the beginning and get an extensible and modular device, which “grows” as you progress. A sufficiently modular microscope can be expanded as needed. Others say that it is probably better not to invest too much during the learning phase. Later you may know much better what your expectations and are then able to make a mor refined choice.
If you are serious about picking up microscopy as a hobby, then I would not buy toy microscopes and USB microscopes which need to be attached to a computer for you to see a picture. If cost is indeed an issue, then I would buy a stereo miroscope instead, they are generally a bit cheaper than compound microscopes.
Much depends also on how much you want to spend. Good used microscopes can already be bought for US$ 200-300, even some new, useful educational microscopes are in this price range. Some people will be happy with these for many years.
I would probably say that one should not invest too much at the beginning, but that one should not go for the cheapest solution either. One can always buy something better later on, based on one’s interests and needs. Often these interests develop over time. It is not uncommon for hobbyists to own several microscopes.