$300 to $600

There are some very nice microscopes in this price range.

Here you will find microscopes with excellent ergonomics, such as angled eyepieces and low coaxial controls for both focusing and mechanical stage movement.

You generally won't find PLAN apochromatic objectives, but standard achromatic objectives will serve you very well until you get into serious photomicrography, and even then there are some work-arounds using computers that can eliminate many of the drawbacks, as long as the subject isn't moving.

You will occasionally find Kohler illumination in this price range.  You will usually find upgradable microscopes with kits for high power dark field condensers, phase contrast kits, polarization kits, and photography attachments.